A English

Relationship between Zeroes and Coefficients of a Polynomial Questions in English

Class 10 Mathematics · Polynomials · Relationship between Zeroes and Coefficients of a Polynomial

186+

Questions

English

Language

100%

With Solutions

Showing 50 of 186 questions in English

1
Medium
Find the zeroes of the quadratic polynomial $x^{2}+7x+10$,and verify the relationship between the zeroes and the coefficients.

Solution

(N/A) We have the quadratic polynomial $p(x) = x^{2}+7x+10$.
To find the zeroes,we set $p(x) = 0$:
$x^{2}+7x+10 = 0$
$x^{2}+5x+2x+10 = 0$
$x(x+5)+2(x+5) = 0$
$(x+2)(x+5) = 0$
Thus,the zeroes are $x = -2$ and $x = -5$.
Verification:
Sum of zeroes $= (-2) + (-5) = -7 = \frac{-7}{1} = \frac{-(\text{Coefficient of } x)}{\text{Coefficient of } x^{2}}$.
Product of zeroes $= (-2) \times (-5) = 10 = \frac{10}{1} = \frac{\text{Constant term}}{\text{Coefficient of } x^{2}}$.
Hence,the relationship is verified.
2
Difficult
Find a quadratic polynomial,the sum and product of whose zeroes are $-3$ and $2,$ respectively.

Solution

(A) Let the quadratic polynomial be $p(x) = ax^2 + bx + c,$ and its zeroes be $\alpha$ and $\beta$.
The relationship between the zeroes and coefficients of a quadratic polynomial is given by:
Sum of zeroes: $\alpha + \beta = -\frac{b}{a} = -3$
Product of zeroes: $\alpha \beta = \frac{c}{a} = 2$
If we assume $a = 1$,then:
$-b = -3 \implies b = 3$
$c = 2$
Substituting these values into the standard form $ax^2 + bx + c$,we get the polynomial $x^2 + 3x + 2$.
Thus,the required quadratic polynomial is $x^2 + 3x + 2$.
3
Difficult
Verify that $3, -1, -\frac{1}{3}$ are the zeroes of the cubic polynomial $p(x) = 3x^3 - 5x^2 - 11x - 3$,and then verify the relationship between the zeroes and the coefficients.

Solution

(A) Comparing the given polynomial $p(x) = 3x^3 - 5x^2 - 11x - 3$ with the standard form $ax^3 + bx^2 + cx + d$,we get $a = 3, b = -5, c = -11, d = -3$.
First,we verify the zeroes:
$p(3) = 3(3)^3 - 5(3)^2 - 11(3) - 3 = 81 - 45 - 33 - 3 = 0$
$p(-1) = 3(-1)^3 - 5(-1)^2 - 11(-1) - 3 = -3 - 5 + 11 - 3 = 0$
$p(-\frac{1}{3}) = 3(-\frac{1}{3})^3 - 5(-\frac{1}{3})^2 - 11(-\frac{1}{3}) - 3 = -\frac{1}{9} - \frac{5}{9} + \frac{11}{3} - 3 = -\frac{6}{9} + \frac{33}{9} - \frac{27}{9} = 0$
Thus,$3, -1, -\frac{1}{3}$ are the zeroes.
Let $\alpha = 3, \beta = -1, \gamma = -\frac{1}{3}$.
$1$. Sum of zeroes: $\alpha + \beta + \gamma = 3 - 1 - \frac{1}{3} = 2 - \frac{1}{3} = \frac{5}{3} = -\frac{b}{a}$.
$2$. Sum of product of zeroes taken two at a time: $\alpha\beta + \beta\gamma + \gamma\alpha = (3)(-1) + (-1)(-\frac{1}{3}) + (-\frac{1}{3})(3) = -3 + \frac{1}{3} - 1 = -4 + \frac{1}{3} = -\frac{11}{3} = \frac{c}{a}$.
$3$. Product of zeroes: $\alpha\beta\gamma = (3)(-1)(-\frac{1}{3}) = 1 = -\frac{d}{a} = -(\frac{-3}{3}) = 1$.
All relationships are verified.
4
Difficult
Find the zeroes of the following quadratic polynomial and verify the relationship between the zeroes and the coefficients: $x^{2}-2x-8$.

Solution

(N/A) Given polynomial: $p(x) = x^{2}-2x-8$.
To find the zeroes,we set $p(x) = 0$:
$x^{2}-2x-8 = 0$
$x^{2}-4x+2x-8 = 0$
$x(x-4)+2(x-4) = 0$
$(x-4)(x+2) = 0$
Thus,the zeroes are $x = 4$ and $x = -2$.
Verification:
Comparing $x^{2}-2x-8$ with $ax^{2}+bx+c$,we get $a=1, b=-2, c=-8$.
Sum of zeroes $= 4 + (-2) = 2$.
Formula: $-b/a = -(-2)/1 = 2$.
Since $2 = 2$,the sum of zeroes is verified.
Product of zeroes $= 4 \times (-2) = -8$.
Formula: $c/a = -8/1 = -8$.
Since $-8 = -8$,the product of zeroes is verified.
5
Medium
Find the zeroes of the quadratic polynomial $4s^{2}-4s+1$ and verify the relationship between the zeroes and the coefficients.

Solution

(N/A) Given polynomial: $p(s) = 4s^{2}-4s+1$.
To find the zeroes,set $p(s) = 0$:
$4s^{2}-4s+1 = 0$
$(2s-1)^{2} = 0$
$2s-1 = 0 \implies s = \frac{1}{2}$.
Thus,the zeroes are $\frac{1}{2}$ and $\frac{1}{2}$.
Verification:
Sum of zeroes $= \frac{1}{2} + \frac{1}{2} = 1 = \frac{-(-4)}{4} = \frac{-(\text{Coefficient of } s)}{\text{Coefficient of } s^{2}}$.
Product of zeroes $= \frac{1}{2} \times \frac{1}{2} = \frac{1}{4} = \frac{\text{Constant term}}{\text{Coefficient of } s^{2}}$.
Hence,the relationship is verified.
6
Medium
Find the zeroes of the following quadratic polynomial and verify the relationship between the zeroes and the coefficients: $6x^{2}-3-7x$.

Solution

(N/A) First,rewrite the polynomial in standard form: $6x^{2}-7x-3$.
To find the zeroes,factorize the quadratic polynomial:
$6x^{2}-7x-3 = 6x^{2}-9x+2x-3 = 3x(2x-3)+1(2x-3) = (3x+1)(2x-3)$.
The value of $6x^{2}-7x-3$ is zero when $3x+1=0$ or $2x-3=0$,which gives $x = -1/3$ or $x = 3/2$.
Therefore,the zeroes are $\alpha = -1/3$ and $\beta = 3/2$.
Verification of the relationship between zeroes and coefficients:
Sum of zeroes: $\alpha + \beta = -1/3 + 3/2 = (-2+9)/6 = 7/6 = -(-7)/6 = -(\text{Coefficient of } x) / (\text{Coefficient of } x^{2})$.
Product of zeroes: $\alpha \times \beta = (-1/3) \times (3/2) = -3/6 = -1/2 = -3/6 = (\text{Constant term}) / (\text{Coefficient of } x^{2})$.
7
Medium
Find the zeroes of the following quadratic polynomial and verify the relationship between the zeroes and the coefficients: $4u^{2} + 8u$.

Solution

(N/A) Given polynomial: $p(u) = 4u^{2} + 8u$.
To find the zeroes,set $p(u) = 0$:
$4u^{2} + 8u = 0$
$4u(u + 2) = 0$
This implies $4u = 0$ or $u + 2 = 0$.
So,$u = 0$ or $u = -2$.
The zeroes are $0$ and $-2$.
Verification:
Comparing $4u^{2} + 8u$ with $au^{2} + bu + c$,we get $a = 4, b = 8, c = 0$.
Sum of zeroes $= 0 + (-2) = -2$.
Relationship: $\frac{-b}{a} = \frac{-8}{4} = -2$.
Since Sum of zeroes $= \frac{-b}{a}$,the relationship is verified.
Product of zeroes $= 0 \times (-2) = 0$.
Relationship: $\frac{c}{a} = \frac{0}{4} = 0$.
Since Product of zeroes $= \frac{c}{a}$,the relationship is verified.
8
Difficult
Find the zeroes of the quadratic polynomial $t^{2}-15$ and verify the relationship between the zeroes and the coefficients.

Solution

(N/A) Given polynomial: $p(t) = t^{2}-15$.
To find the zeroes,set $p(t) = 0$:
$t^{2}-15 = 0$
$t^{2} = 15$
$t = \pm \sqrt{15}$
So,the zeroes are $\alpha = \sqrt{15}$ and $\beta = -\sqrt{15}$.
Comparing $t^{2}-15$ with the standard form $at^{2}+bt+c$,we get $a=1, b=0, c=-15$.
Verification:
Sum of zeroes: $\alpha + \beta = \sqrt{15} + (-\sqrt{15}) = 0$.
From coefficients: $\frac{-b}{a} = \frac{-0}{1} = 0$.
Thus,$\alpha + \beta = \frac{-b}{a}$ is verified.
Product of zeroes: $\alpha \cdot \beta = (\sqrt{15})(-\sqrt{15}) = -15$.
From coefficients: $\frac{c}{a} = \frac{-15}{1} = -15$.
Thus,$\alpha \cdot \beta = \frac{c}{a}$ is verified.
9
Easy
Find the zeroes of the quadratic polynomial $3x^{2}-x-4$ and verify the relationship between the zeroes and the coefficients.

Solution

(N/A) Given polynomial: $p(x) = 3x^{2}-x-4$.
To find the zeroes,we set $p(x) = 0$:
$3x^{2}-x-4 = 0$
$3x^{2}-4x+3x-4 = 0$
$x(3x-4)+1(3x-4) = 0$
$(3x-4)(x+1) = 0$
Thus,the zeroes are $x = \frac{4}{3}$ and $x = -1$.
Verification:
Sum of zeroes $= \frac{4}{3} + (-1) = \frac{4-3}{3} = \frac{1}{3}$.
From the polynomial,$-\frac{\text{coefficient of } x}{\text{coefficient of } x^{2}} = -\frac{-1}{3} = \frac{1}{3}$.
Since $\frac{1}{3} = \frac{1}{3}$,the sum is verified.
Product of zeroes $= \frac{4}{3} \times (-1) = -\frac{4}{3}$.
From the polynomial,$\frac{\text{constant term}}{\text{coefficient of } x^{2}} = \frac{-4}{3}$.
Since $-\frac{4}{3} = -\frac{4}{3}$,the product is verified.
10
EasyMCQ
Find a quadratic polynomial with the given numbers as the sum and product of its zeroes respectively: $\frac{1}{4}, -1$.
A
$4x^2 - x - 4$
B
$x^2 + x - 4$
C
$4x^2 + x - 4$
D
$x^2 - x + 4$

Solution

(A) Let the quadratic polynomial be $ax^2 + bx + c$ and its zeroes be $\alpha$ and $\beta$.
Given that the sum of zeroes $\alpha + \beta = \frac{1}{4}$ and the product of zeroes $\alpha \beta = -1$.
We know that a quadratic polynomial can be expressed as $k[x^2 - (\alpha + \beta)x + \alpha \beta]$,where $k$ is a non-zero constant.
Substituting the given values,we get $k[x^2 - (\frac{1}{4})x + (-1)]$.
To simplify,let $k = 4$.
Then the polynomial becomes $4[x^2 - \frac{1}{4}x - 1] = 4x^2 - x - 4$.
Thus,the required quadratic polynomial is $4x^2 - x - 4$.
11
Medium
Find a quadratic polynomial,each with the given numbers as the sum and product of its zeroes respectively: $\sqrt{2}, \frac{1}{3}$.

Solution

(D) Let the quadratic polynomial be $p(x) = ax^2 + bx + c$,and its zeroes be $\alpha$ and $\beta$.
The sum of the zeroes is given by $\alpha + \beta = \sqrt{2} = -\frac{b}{a}$.
The product of the zeroes is given by $\alpha \beta = \frac{1}{3} = \frac{c}{a}$.
To express these with a common denominator $a$,we write $\alpha + \beta = \frac{3\sqrt{2}}{3} = -\frac{b}{a}$.
Comparing the coefficients,we get $a = 3$,$b = -3\sqrt{2}$,and $c = 1$.
Substituting these values into the general form $ax^2 + bx + c$,we get the quadratic polynomial $3x^2 - 3\sqrt{2}x + 1$.
12
Easy
Find a quadratic polynomial,each with the given numbers as the sum and product of its zeroes respectively: $0, \sqrt{5}$.

Solution

(D) Let the quadratic polynomial be $p(x) = ax^2 + bx + c$,and its zeroes be $\alpha$ and $\beta$.
The sum of the zeroes is given by $\alpha + \beta = 0 = \frac{0}{1} = -\frac{b}{a}$.
The product of the zeroes is given by $\alpha \times \beta = \sqrt{5} = \frac{\sqrt{5}}{1} = \frac{c}{a}$.
Comparing the coefficients,if we take $a = 1$,then $b = 0$ and $c = \sqrt{5}$.
Substituting these values into the general form $ax^2 + bx + c$,we get the quadratic polynomial $x^2 + 0x + \sqrt{5}$,which simplifies to $x^2 + \sqrt{5}$.
13
Easy
Find a quadratic polynomial,each with the given numbers as the sum and product of its zeroes respectively: $1, 1$.

Solution

(A) Let the quadratic polynomial be $p(x) = ax^2 + bx + c$,and its zeroes be $\alpha$ and $\beta$.
The sum of zeroes is given by $\alpha + \beta = 1 = \frac{-b}{a}$.
The product of zeroes is given by $\alpha \times \beta = 1 = \frac{c}{a}$.
If we assume $a = 1$,then:
$-b = 1 \implies b = -1$
$c = 1$
Substituting these values into the general form $ax^2 + bx + c$,we get the polynomial $x^2 - x + 1$.
14
MediumMCQ
Find a quadratic polynomial,each with the given numbers as the sum and product of its zeroes respectively: $-\frac{1}{4}, \frac{1}{4}$.
A
$4x^2 + x + 1$
B
$4x^2 - x + 1$
C
$x^2 + x + 1$
D
$4x^2 + x - 1$

Solution

(A) Let the quadratic polynomial be $p(x) = ax^2 + bx + c$,and its zeroes be $\alpha$ and $\beta$.
The sum of zeroes is given by $\alpha + \beta = -\frac{1}{4} = -\frac{b}{a}$.
The product of zeroes is given by $\alpha \times \beta = \frac{1}{4} = \frac{c}{a}$.
Comparing the ratios,if we take $a = 4$,then $b = 1$ and $c = 1$.
Substituting these values into the general form $ax^2 + bx + c$,we get the polynomial $4x^2 + x + 1$.
15
Medium
Find a quadratic polynomial with the given numbers as the sum and product of its zeroes respectively: $4, 1$.

Solution

(A) Let the quadratic polynomial be $p(x) = ax^2 + bx + c$,where $\alpha$ and $\beta$ are its zeroes.
The sum of the zeroes is given by $\alpha + \beta = 4 = \frac{4}{1} = \frac{-b}{a}$.
The product of the zeroes is given by $\alpha \times \beta = 1 = \frac{1}{1} = \frac{c}{a}$.
By comparing the ratios,if we assume $a = 1$,then $b = -4$ and $c = 1$.
Substituting these values into the general form $ax^2 + bx + c$,we get the quadratic polynomial $x^2 - 4x + 1$.
16
Difficult
Obtain all other zeroes of $3x^{4} + 6x^{3} - 2x^{2} - 10x - 5$,if two of its zeroes are $\sqrt{\frac{5}{3}}$ and $-\sqrt{\frac{5}{3}}$.

Solution

(N/A) Let $p(x) = 3x^{4} + 6x^{3} - 2x^{2} - 10x - 5$.
Since $\sqrt{\frac{5}{3}}$ and $-\sqrt{\frac{5}{3}}$ are two zeroes of $p(x)$,then $(x - \sqrt{\frac{5}{3}})(x + \sqrt{\frac{5}{3}}) = (x^{2} - \frac{5}{3})$ is a factor of $p(x)$.
To find the other zeroes,we divide $p(x)$ by $(x^{2} - \frac{5}{3})$:
$3x^{4} + 6x^{3} - 2x^{2} - 10x - 5 = (x^{2} - \frac{5}{3})(3x^{2} + 6x + 3)$
$= 3(x^{2} - \frac{5}{3})(x^{2} + 2x + 1)$
$= 3(x^{2} - \frac{5}{3})(x + 1)^{2}$
Now,to find the remaining zeroes,we set $(x + 1)^{2} = 0$,which gives $x + 1 = 0$,so $x = -1$.
Since the factor is $(x + 1)^{2}$,the zero $x = -1$ is repeated twice.
Thus,the other two zeroes of the polynomial are $-1$ and $-1$.
Solution diagram
17
MediumMCQ
If one zero of the quadratic polynomial $x^{2}+3x+k$ is $2$,then the value of $k$ is
A
$-10$
B
$10$
C
$5$
D
$-5$

Solution

(A) Let the polynomial be $p(x) = x^{2} + 3x + k$.
Since $2$ is a zero of the polynomial,$p(2) = 0$.
Substituting $x = 2$ into the polynomial:
$p(2) = (2)^{2} + 3(2) + k = 0$
$4 + 6 + k = 0$
$10 + k = 0$
$k = -10$
18
MediumMCQ
Given that two of the zeroes of the cubic polynomial $ax^3 + bx^2 + cx + d$ are $0$, the third zero is
A
$\frac{b}{a}$
B
$\frac{-b}{a}$
C
$\frac{c}{a}$
D
$-\frac{d}{a}$

Solution

(B) Let the zeroes of the cubic polynomial $p(x) = ax^3 + bx^2 + cx + d$ be $\alpha, \beta,$ and $\gamma$.
Given that two zeroes are $0$, let $\alpha = 0$ and $\beta = 0$.
The sum of the zeroes of a cubic polynomial is given by $\alpha + \beta + \gamma = -\frac{b}{a}$.
Substituting $\alpha = 0$ and $\beta = 0$ into the equation, we get $0 + 0 + \gamma = -\frac{b}{a}$.
Therefore, the third zero is $\gamma = -\frac{b}{a}$.
19
MediumMCQ
If one of the zeroes of the quadratic polynomial $(k-1) x^{2}+k x+1$ is $-3,$ then the value of $k$ is
A
$\frac{2}{3}$
B
$\frac{-2}{3}$
C
$\frac{4}{3}$
D
$\frac{-4}{3}$

Solution

(C) Given that,one of the zeroes of the quadratic polynomial $p(x) = (k-1)x^2 + kx + 1$ is $-3$.
Therefore,$p(-3) = 0$.
Substituting $x = -3$ in the polynomial:
$(k-1)(-3)^2 + k(-3) + 1 = 0$
$9(k-1) - 3k + 1 = 0$
$9k - 9 - 3k + 1 = 0$
$6k - 8 = 0$
$6k = 8$
$k = \frac{8}{6} = \frac{4}{3}$
20
DifficultMCQ
$A$ quadratic polynomial, whose zeroes are $-3$ and $4,$ is
A
$x^{2}-x+12$
B
$x^{2}+x+12$
C
$2x^{2}+2x-24$
D
$\frac{x^{2}}{2}-\frac{x}{2}-6$

Solution

(D) Let the quadratic polynomial be $p(x) = k(x^2 - (\text{sum of zeroes})x + (\text{product of zeroes}))$, where $k$ is a non-zero constant.
Given zeroes are $\alpha = -3$ and $\beta = 4$.
Sum of zeroes $(\alpha + \beta) = -3 + 4 = 1$.
Product of zeroes $(\alpha \cdot \beta) = -3 \times 4 = -12$.
Substituting these values into the formula, we get $p(x) = k(x^2 - 1x + (-12)) = k(x^2 - x - 12)$.
If we choose $k = \frac{1}{2}$, the polynomial becomes $\frac{1}{2}(x^2 - x - 12) = \frac{x^2}{2} - \frac{x}{2} - 6$.
Since the zeroes of a polynomial remain unchanged when multiplied by a non-zero constant, option $D$ is a valid quadratic polynomial with the given zeroes.
21
DifficultMCQ
If the zeroes of the quadratic polynomial $x^{2}+(a+1)x+b$ are $2$ and $-3$,then
A
$a=0, b=-6$
B
$a=2, b=-6$
C
$a=5, b=-1$
D
$a=-7, b=-1$

Solution

(A) Let $p(x) = x^{2} + (a+1)x + b$.
Given that $2$ and $-3$ are the zeroes of the quadratic polynomial $p(x)$.
Therefore,$p(2) = 0$ and $p(-3) = 0$.
For $x = 2$:
$2^{2} + (a+1)(2) + b = 0$
$4 + 2a + 2 + b = 0$
$2a + b = -6$ ..... $(i)$
For $x = -3$:
$(-3)^{2} + (a+1)(-3) + b = 0$
$9 - 3a - 3 + b = 0$
$-3a + b = -6$ ..... $(ii)$
Subtracting equation $(ii)$ from equation $(i)$:
$(2a + b) - (-3a + b) = -6 - (-6)$
$2a + b + 3a - b = 0$
$5a = 0 \Rightarrow a = 0$.
Substituting $a = 0$ in equation $(i)$:
$2(0) + b = -6 \Rightarrow b = -6$.
Thus,the required values are $a = 0$ and $b = -6$.
22
DifficultMCQ
The number of polynomials having zeroes as $-2$ and $5$ is
A
$3$
B
more than $3$
C
$1$
D
$2$

Solution

(B) Let $p(x) = a(x^2 - (\text{sum of zeroes})x + (\text{product of zeroes}))$ be the general form of the polynomial.
Given zeroes are $\alpha = -2$ and $\beta = 5$.
Sum of zeroes $= \alpha + \beta = -2 + 5 = 3$.
Product of zeroes $= \alpha \cdot \beta = -2 \times 5 = -10$.
Thus, the polynomial is of the form $p(x) = a(x^2 - 3x - 10)$, where $a$ is any non-zero real constant.
Since $a$ can take any non-zero real value (e.g., $1, 2, 3, \dots, 0.5, \dots$), there are infinitely many such polynomials.
Therefore, the number of such polynomials is more than $3$.
23
MediumMCQ
Given that one of the zeroes of the cubic polynomial $ax^3 + bx^2 + cx + d$ is zero,the product of the other two zeroes is
A
$-\frac{c}{a}$
B
$0$
C
$\frac{c}{a}$
D
$-\frac{b}{a}$

Solution

(C) Let $p(x) = ax^3 + bx^2 + cx + d$ be the cubic polynomial.
Let the zeroes of the polynomial be $\alpha, \beta,$ and $\gamma$.
Given that one of the zeroes is zero,let $\alpha = 0$.
According to the relationship between zeroes and coefficients of a cubic polynomial,the sum of the product of zeroes taken two at a time is given by $\alpha\beta + \beta\gamma + \gamma\alpha = \frac{c}{a}$.
Substituting $\alpha = 0$ into the equation:
$(0)\beta + \beta\gamma + \gamma(0) = \frac{c}{a}$
$0 + \beta\gamma + 0 = \frac{c}{a}$
$\beta\gamma = \frac{c}{a}$
Thus,the product of the other two zeroes is $\frac{c}{a}$.
24
DifficultMCQ
If one of the zeroes of the cubic polynomial $x^{3}+a x^{2}+b x+c$ is $-1,$ then the product of the other two zeroes is
A
$a-b-1$
B
$b-a-1$
C
$a-b+1$
D
$b-a+1$

Solution

(D) Let the cubic polynomial be $p(x) = x^{3} + a x^{2} + b x + c$.
Let the zeroes of the polynomial be $\alpha, \beta,$ and $\gamma$.
Given that one zero is $\alpha = -1$.
Since $\alpha = -1$ is a zero,$p(-1) = 0$.
Substituting $x = -1$ into the polynomial:
$(-1)^{3} + a(-1)^{2} + b(-1) + c = 0$
$-1 + a - b + c = 0$
$c = 1 - a + b$ ... $(i)$
We know that for a cubic polynomial $Ax^{3} + Bx^{2} + Cx + D$,the product of the zeroes is given by $-\frac{D}{A}$.
Here,the product of the zeroes is $\alpha \cdot \beta \cdot \gamma = -\frac{c}{1} = -c$.
Substituting $\alpha = -1$:
$(-1) \cdot \beta \cdot \gamma = -c$
$\beta \cdot \gamma = c$.
Substituting the value of $c$ from equation $(i)$:
$\beta \cdot \gamma = 1 - a + b$.
Thus,the product of the other two zeroes is $b - a + 1$.
25
MediumMCQ
The zeroes of the quadratic polynomial $x^{2}+99x+127$ are
A
both negative
B
both positive
C
one positive and one negative
D
both equal

Solution

(A) Let the given quadratic polynomial be $p(x) = x^{2} + 99x + 127$.
Comparing $p(x)$ with the standard form $ax^{2} + bx + c$,we get $a = 1$,$b = 99$,and $c = 127$.
For a quadratic polynomial $ax^{2} + bx + c$,if $a, b, c > 0$,then the product of zeroes $\alpha \beta = \frac{c}{a} = 127 > 0$ and the sum of zeroes $\alpha + \beta = -\frac{b}{a} = -99 < 0$.
Since the product of the zeroes is positive,both zeroes must have the same sign.
Since the sum of the zeroes is negative,both zeroes must be negative.
Alternatively,using the quadratic formula $x = \frac{-b \pm \sqrt{b^{2} - 4ac}}{2a}$:
$x = \frac{-99 \pm \sqrt{99^{2} - 4(1)(127)}}{2(1)} = \frac{-99 \pm \sqrt{9801 - 508}}{2} = \frac{-99 \pm \sqrt{9293}}{2}$.
Since $\sqrt{9293} \approx 96.4$,the roots are approximately $\frac{-99 + 96.4}{2} = -1.3$ and $\frac{-99 - 96.4}{2} = -97.7$.
Thus,both zeroes are negative.
26
DifficultMCQ
The zeroes of the quadratic polynomial $x^{2}+kx+k, k \neq 0,$
A
cannot both be negative
B
cannot both be positive
C
are always unequal
D
are always equal

Solution

(B) Let $p(x) = x^{2} + kx + k, k \neq 0$.
For the zeroes to be real,the discriminant $D$ must be greater than or equal to $0$.
$D = b^{2} - 4ac = k^{2} - 4k \geq 0$.
$k(k - 4) \geq 0$.
This implies $k \in (-\infty, 0] \cup [4, \infty)$. Since $k \neq 0$,$k \in (-\infty, 0) \cup [4, \infty)$.
Let the zeroes be $\alpha$ and $\beta$. Then:
Sum of zeroes $\alpha + \beta = -k/1 = -k$.
Product of zeroes $\alpha \beta = k/1 = k$.
Case $I$: If $k \in (-\infty, 0)$,then $k < 0$. Since the product $\alpha \beta = k < 0$,the zeroes must have opposite signs.
Case $II$: If $k \in [4, \infty)$,then $k > 0$. Since the product $\alpha \beta = k > 0$,both zeroes have the same sign. The sum $\alpha + \beta = -k < 0$,so both zeroes must be negative.
In both cases,the zeroes cannot both be positive.
Solution diagram
27
MediumMCQ
If the zeroes of the quadratic polynomial $ax^{2} + bx + c, c \neq 0$ are equal,then
A
$c$ and $a$ have opposite signs
B
$c$ and $b$ have opposite signs
C
$c$ and $a$ have the same sign
D
$c$ and $b$ have the same sign

Solution

(C) For a quadratic polynomial $ax^{2} + bx + c$,the zeroes are equal if the discriminant $D = b^{2} - 4ac = 0$.
This implies $b^{2} = 4ac$.
Since $b^{2}$ is always non-negative for any real $b$,$4ac$ must be non-negative.
Given $c \neq 0$,if $a = 0$,it would not be a quadratic polynomial. Thus,$a \neq 0$.
Since $4ac = b^{2} \geq 0$,the product $ac$ must be greater than or equal to $0$.
Since $c \neq 0$ and $a \neq 0$,$ac > 0$,which means $a$ and $c$ must have the same sign.
For example:
$(i)$ $x^{2} + 4x + 4 = 0 \Rightarrow (x+2)^{2} = 0 \Rightarrow x = -2, -2$ (Here $a=1, c=4$,both positive).
$(ii)$ $x^{2} - 4x + 4 = 0 \Rightarrow (x-2)^{2} = 0 \Rightarrow x = 2, 2$ (Here $a=1, c=4$,both positive).
28
DifficultMCQ
If one of the zeroes of a quadratic polynomial of the form $x^{2}+ax+b$ is the negative of the other,then it
A
can have a linear term but the constant term is positive
B
has no linear term and the constant term is positive
C
can have a linear term but the constant term is negative
D
has no linear term and the constant term is negative

Solution

(D) Let the zeroes of the quadratic polynomial $p(x) = x^{2} + ax + b$ be $\alpha$ and $-\alpha$.
Sum of zeroes = $-\frac{\text{coefficient of } x}{\text{coefficient of } x^{2}} = -a$.
Since $\alpha + (-\alpha) = 0$,we have $0 = -a$,which implies $a = 0$.
Product of zeroes = $\frac{\text{constant term}}{\text{coefficient of } x^{2}} = b$.
Since $\alpha \times (-\alpha) = -\alpha^{2}$,we have $-\alpha^{2} = b$.
Since $\alpha^{2}$ is always positive for non-zero $\alpha$,$- \alpha^{2}$ must be negative,so $b < 0$.
Therefore,the polynomial has no linear term $(a = 0)$ and the constant term is negative $(b < 0)$.
29
EasyMCQ
Is the following statement True or False? Justify your answer. If the zeroes of a quadratic polynomial $ax^2 + bx + c$ are both negative,then $a, b,$ and $c$ all have the same sign.
A
True
B
False

Solution

(A) The statement is True.
Let the zeroes of the quadratic polynomial $p(x) = ax^2 + bx + c$ be $\alpha$ and $\beta$,where $\alpha < 0$ and $\beta < 0$.
From the relationship between zeroes and coefficients:
$1$. The sum of the zeroes is $\alpha + \beta = -\frac{b}{a}$. Since both $\alpha$ and $\beta$ are negative,their sum $(\alpha + \beta)$ must be negative. Therefore,$-\frac{b}{a} < 0$,which implies $\frac{b}{a} > 0$. This means $a$ and $b$ must have the same sign.
$2$. The product of the zeroes is $\alpha \cdot \beta = \frac{c}{a}$. Since the product of two negative numbers is positive,$\frac{c}{a} > 0$. This means $a$ and $c$ must have the same sign.
Since $a$ and $b$ have the same sign,and $a$ and $c$ have the same sign,it follows that $a, b,$ and $c$ all have the same sign.
30
Easy
Answer the following and justify:
If on division of a polynomial $p(x)$ by a polynomial $g(x)$,the quotient is zero,what is the relation between the degrees of $p(x)$ and $g(x)$?

Solution

(N/A) According to the division algorithm for polynomials,$p(x) = g(x) \cdot q(x) + r(x)$,where $q(x)$ is the quotient and $r(x)$ is the remainder.
Given that the quotient $q(x) = 0$,the equation becomes $p(x) = g(x) \cdot 0 + r(x)$,which simplifies to $p(x) = r(x)$.
In polynomial division,the degree of the remainder $r(x)$ must be strictly less than the degree of the divisor $g(x)$,i.e.,$\text{deg}(r(x)) < \text{deg}(g(x))$.
Since $p(x) = r(x)$,it follows that $\text{deg}(p(x)) < \text{deg}(g(x))$.
Therefore,the degree of $p(x)$ is less than the degree of $g(x)$.
31
Medium
Are the following statements 'True' or 'False'? Justify your answers.
If the zeroes of a quadratic polynomial $ax^2 + bx + c$ are both positive,then $a, b$ and $c$ all have the same sign.

Solution

(B) The statement is False.
Let the zeroes of the quadratic polynomial $ax^2 + bx + c$ be $\alpha$ and $\beta$. Since both zeroes are positive,$\alpha > 0$ and $\beta > 0$.
From the relationship between zeroes and coefficients:
$1$. The product of zeroes $\alpha \cdot \beta = \frac{c}{a}$. Since $\alpha > 0$ and $\beta > 0$,their product $\alpha \cdot \beta > 0$. Therefore,$\frac{c}{a} > 0$,which means $a$ and $c$ must have the same sign.
$2$. The sum of zeroes $\alpha + \beta = -\frac{b}{a}$. Since $\alpha > 0$ and $\beta > 0$,their sum $\alpha + \beta > 0$. Therefore,$-\frac{b}{a} > 0$,which implies $\frac{b}{a} < 0$. This means $a$ and $b$ must have opposite signs.
Thus,$a$ and $c$ have the same sign,but $b$ has the opposite sign to $a$ and $c$. Hence,$a, b,$ and $c$ do not all have the same sign.
32
MediumMCQ
Are the following statements 'True' or 'False'? Justify your answers.
If two of the zeroes of a cubic polynomial are zero,then it does not have linear and constant terms.
A
True
B
False

Solution

(A) True. Let the zeroes of the cubic polynomial be $\alpha, \beta,$ and $\gamma$. It is given that two of the zeroes are $0$. Let $\alpha = 0$ and $\beta = 0$.
The cubic polynomial can be expressed as $f(x) = k(x - \alpha)(x - \beta)(x - \gamma)$,where $k$ is a non-zero constant.
Substituting the values: $f(x) = k(x - 0)(x - 0)(x - \gamma) = k(x^2)(x - \gamma) = k(x^3 - \gamma x^2) = kx^3 - k\gamma x^2$.
Comparing this with the general form $ax^3 + bx^2 + cx + d$,we see that the coefficients of the linear term $(c)$ and the constant term $(d)$ are both $0$. Thus,the polynomial does not have linear and constant terms.
33
Easy
Are the following statements 'True' or 'False'? Justify your answers.
If all the zeroes of a cubic polynomial are negative,then all the coefficients and the constant term of the polynomial have the same sign.

Solution

(A) The statement is True.
Let the cubic polynomial be $f(x) = a(x - \alpha)(x - \beta)(x - \gamma)$,where $\alpha, \beta, \gamma < 0$ are the negative zeroes.
Let $\alpha = -p, \beta = -q, \gamma = -r$,where $p, q, r > 0$.
Then $f(x) = a(x + p)(x + q)(x + r)$.
Expanding this,we get $f(x) = a[x^3 + (p + q + r)x^2 + (pq + qr + rp)x + pqr]$.
Comparing this with the standard form $f(x) = ax^3 + bx^2 + cx + d$,we get:
$b = a(p + q + r)$
$c = a(pq + qr + rp)$
$d = a(pqr)$
Since $p, q, r > 0$,the terms $(p + q + r)$,$(pq + qr + rp)$,and $(pqr)$ are all positive.
Therefore,$a, b, c,$ and $d$ all have the same sign as $a$.
34
Difficult
Are the following statements 'True' or 'False'? Justify your answers.
If all three zeroes of a cubic polynomial $x^{3}+ax^{2}-bx+c$ are positive,then at least one of $a, b$ and $c$ is non-negative.

Solution

(B) False. Let $\alpha, \beta$ and $\gamma$ be the three zeroes of the cubic polynomial $p(x) = x^{3}+ax^{2}-bx+c$.
According to the relationship between zeroes and coefficients:
$1$. Product of zeroes: $\alpha \beta \gamma = -\frac{c}{1} = -c$. Since $\alpha, \beta, \gamma > 0$,their product $\alpha \beta \gamma > 0$. Therefore,$-c > 0$,which implies $c < 0$.
$2$. Sum of zeroes: $\alpha + \beta + \gamma = -\frac{a}{1} = -a$. Since $\alpha, \beta, \gamma > 0$,their sum $\alpha + \beta + \gamma > 0$. Therefore,$-a > 0$,which implies $a < 0$.
$3$. Sum of product of zeroes taken two at a time: $\alpha \beta + \beta \gamma + \gamma \alpha = \frac{-b}{1} = -b$. Since $\alpha, \beta, \gamma > 0$,their sum of products $\alpha \beta + \beta \gamma + \gamma \alpha > 0$. Therefore,$-b > 0$,which implies $b < 0$.
Thus,for all three zeroes to be positive,$a, b$ and $c$ must all be negative. Hence,the statement that at least one of them is non-negative is False.
35
Medium
Find the zeroes of the polynomial $x^{2}+\frac{1}{6} x-2,$ and verify the relation between the coefficients and the zeroes of the polynomial.

Solution

(A) To find the zeroes,set the polynomial to zero: $x^{2}+\frac{1}{6} x-2 = 0$.
Multiply by $6$ to simplify: $6x^{2}+x-12 = 0$.
Factorizing the quadratic: $6x^{2}+9x-8x-12 = 0$.
$3x(2x+3)-4(2x+3) = 0 \implies (3x-4)(2x+3) = 0$.
Thus,the zeroes are $\alpha = \frac{4}{3}$ and $\beta = -\frac{3}{2}$.
Verification:
Sum of zeroes: $\alpha + \beta = \frac{4}{3} - \frac{3}{2} = \frac{8-9}{6} = -\frac{1}{6}$.
From the polynomial $ax^2+bx+c$,sum $= -\frac{b}{a} = -\frac{1/6}{1} = -\frac{1}{6}$.
Product of zeroes: $\alpha \beta = \frac{4}{3} \times (-\frac{3}{2}) = -2$.
From the polynomial,product $= \frac{c}{a} = \frac{-2}{1} = -2$.
Both relations are verified.
36
Medium
Find the zeroes of the following polynomial by the factorisation method and verify the relationship between the zeroes and the coefficients of the polynomial: $4x^2 - 3x - 1$

Solution

(N/A) Let $f(x) = 4x^2 - 3x - 1$.
To find the zeroes,we factorise the polynomial by splitting the middle term:
$f(x) = 4x^2 - 4x + x - 1$
$f(x) = 4x(x - 1) + 1(x - 1)$
$f(x) = (x - 1)(4x + 1)$
The zeroes are found by setting $f(x) = 0$:
$x - 1 = 0 \implies x = 1$
$4x + 1 = 0 \implies x = -\frac{1}{4}$
Thus,the zeroes are $\alpha = 1$ and $\beta = -\frac{1}{4}$.
Verification:
Sum of zeroes $= \alpha + \beta = 1 + (-\frac{1}{4}) = \frac{3}{4} = -\frac{-3}{4} = -\frac{\text{Coefficient of } x}{\text{Coefficient of } x^2}$.
Product of zeroes $= \alpha \cdot \beta = 1 \cdot (-\frac{1}{4}) = -\frac{1}{4} = \frac{-1}{4} = \frac{\text{Constant term}}{\text{Coefficient of } x^2}$.
Hence,the relationship is verified.
37
Medium
Find the zeroes of the following polynomial by the factorization method and verify the relationship between the zeroes and the coefficients of the polynomial:
$3x^2 + 4x - 4$

Solution

(N/A) Let $f(x) = 3x^2 + 4x - 4$.
To find the zeroes,we factorize the polynomial by splitting the middle term:
$3x^2 + 6x - 2x - 4 = 3x(x + 2) - 2(x + 2) = (x + 2)(3x - 2)$.
The zeroes are found by setting $f(x) = 0$:
$(x + 2)(3x - 2) = 0$,which gives $x = -2$ or $x = \frac{2}{3}$.
Verification:
Sum of zeroes $= -2 + \frac{2}{3} = \frac{-6 + 2}{3} = -\frac{4}{3}$.
From the polynomial $ax^2 + bx + c$,where $a=3, b=4, c=-4$,the sum of zeroes is $-\frac{b}{a} = -\frac{4}{3}$.
Product of zeroes $= (-2) \times \frac{2}{3} = -\frac{4}{3}$.
From the polynomial,the product of zeroes is $\frac{c}{a} = \frac{-4}{3}$.
Since the sum and product match the coefficients,the relationship is verified.
38
Medium
Find the zeroes of the following polynomial by the factorisation method and verify the relationship between the zeroes and the coefficients of the polynomial:
$5 t^{2}+12 t+7$

Solution

(A) Let $f(t) = 5 t^{2}+12 t+7$.
To find the zeroes,we factorise the polynomial by splitting the middle term:
$5 t^{2}+12 t+7 = 5 t^{2}+5 t+7 t+7$
$= 5 t(t+1)+7(t+1)$
$= (5 t+7)(t+1)$
The zeroes are found by setting $f(t) = 0$:
$5 t+7 = 0 \implies t = -7/5$
$t+1 = 0 \implies t = -1$
Thus,the zeroes are $\alpha = -7/5$ and $\beta = -1$.
Verification:
Sum of zeroes $= \alpha + \beta = -7/5 - 1 = -12/5$.
From the polynomial $5 t^{2}+12 t+7$,the coefficient of $t$ is $12$ and the coefficient of $t^{2}$ is $5$.
Sum of zeroes $= -(\text{coefficient of } t) / (\text{coefficient of } t^{2}) = -12/5$.
Product of zeroes $= \alpha \cdot \beta = (-7/5) \cdot (-1) = 7/5$.
From the polynomial,the constant term is $7$ and the coefficient of $t^{2}$ is $5$.
Product of zeroes $= (\text{constant term}) / (\text{coefficient of } t^{2}) = 7/5$.
Hence,the relationship is verified.
39
Difficult
Find the zeroes of the following polynomial by the factorisation method and verify the relationship between the zeroes and the coefficients of the polynomial:
$t^{3}-2 t^{2}-15 t$

Solution

(A) Let $f(t) = t^{3}-2 t^{2}-15 t$.
$= t(t^{2}-2 t-15)$
$= t(t^{2}-5 t+3 t-15)$ [by splitting the middle term]
$= t[t(t-5)+3(t-5)]$
$= t(t-5)(t+3)$
So,the value of $f(t)$ is zero when $t=0$,$t-5=0$,or $t+3=0$.
Thus,the zeroes are $t=0, t=5$,and $t=-3$.
Verification:
Sum of zeroes $= 0 + 5 + (-3) = 2 = -(-2)/1 = -(\text{Coefficient of } t^{2}) / (\text{Coefficient of } t^{3})$.
Sum of product of zeroes taken two at a time $= (0)(5) + (5)(-3) + (-3)(0) = 0 - 15 + 0 = -15 = (-15)/1 = (\text{Coefficient of } t) / (\text{Coefficient of } t^{3})$.
Product of zeroes $= (0)(5)(-3) = 0 = -(0)/1 = -(\text{Constant term}) / (\text{Coefficient of } t^{3})$.
Hence,the relationship is verified.
40
Difficult
Find the zeroes of the following polynomial by the factorisation method and verify the relationship between the zeroes and the coefficients of the polynomial:
$2x^2 + \frac{7}{2}x + \frac{3}{4}$

Solution

(N/A) Let $f(x) = 2x^2 + \frac{7}{2}x + \frac{3}{4}$.
To find the zeroes,we set $f(x) = 0$,so $2x^2 + \frac{7}{2}x + \frac{3}{4} = 0$.
Multiplying the entire equation by $4$,we get $8x^2 + 14x + 3 = 0$.
Splitting the middle term: $8x^2 + 12x + 2x + 3 = 0$.
$4x(2x + 3) + 1(2x + 3) = 0$.
$(2x + 3)(4x + 1) = 0$.
Thus,the zeroes are $x = -\frac{3}{2}$ and $x = -\frac{1}{4}$.
Verification:
Sum of zeroes $= -\frac{3}{2} + (-\frac{1}{4}) = -\frac{6}{4} - \frac{1}{4} = -\frac{7}{4}$.
Coefficient relation: $-\frac{\text{Coefficient of } x}{\text{Coefficient of } x^2} = -\frac{7/2}{2} = -\frac{7}{4}$.
Product of zeroes $= (-\frac{3}{2}) \times (-\frac{1}{4}) = \frac{3}{8}$.
Coefficient relation: $\frac{\text{Constant term}}{\text{Coefficient of } x^2} = \frac{3/4}{2} = \frac{3}{8}$.
Since both relations hold,the relationship is verified.
41
Medium
Find the zeroes of the following polynomial by the factorisation method and verify the relationship between the zeroes and the coefficients of the polynomial: $4x^{2} + 5\sqrt{2}x - 3$

Solution

(N/A) Let $f(x) = 4x^{2} + 5\sqrt{2}x - 3$.
To factorise,we split the middle term: $4x^{2} + 6\sqrt{2}x - \sqrt{2}x - 3$.
$= 2\sqrt{2}x(\sqrt{2}x + 3) - 1(\sqrt{2}x + 3)$.
$= (\sqrt{2}x + 3)(2\sqrt{2}x - 1)$.
Setting $f(x) = 0$,we get $\sqrt{2}x + 3 = 0$ or $2\sqrt{2}x - 1 = 0$.
Thus,the zeroes are $x = -\frac{3}{\sqrt{2}}$ and $x = \frac{1}{2\sqrt{2}}$.
Verification:
Sum of zeroes $= -\frac{3}{\sqrt{2}} + \frac{1}{2\sqrt{2}} = \frac{-6 + 1}{2\sqrt{2}} = -\frac{5}{2\sqrt{2}} = -\frac{5\sqrt{2}}{4}$.
Coefficient of $x$ is $5\sqrt{2}$ and coefficient of $x^{2}$ is $4$. So,$-\frac{\text{Coefficient of } x}{\text{Coefficient of } x^{2}} = -\frac{5\sqrt{2}}{4}$. (Verified)
Product of zeroes $= (-\frac{3}{\sqrt{2}}) \times (\frac{1}{2\sqrt{2}}) = -\frac{3}{4}$.
Constant term is $-3$ and coefficient of $x^{2}$ is $4$. So,$\frac{\text{Constant term}}{\text{Coefficient of } x^{2}} = -\frac{3}{4}$. (Verified)
42
Difficult
Find the zeroes of the following polynomial by the factorisation method and verify the relationship between the zeroes and the coefficients of the polynomial:
$2s^{2} - (1 + 2\sqrt{2})s + \sqrt{2}$

Solution

(N/A) Let $f(s) = 2s^{2} - (1 + 2\sqrt{2})s + \sqrt{2}$.
$= 2s^{2} - s - 2\sqrt{2}s + \sqrt{2}$
$= s(2s - 1) - \sqrt{2}(2s - 1)$
$= (2s - 1)(s - \sqrt{2})$
The value of $f(s)$ is zero when $2s - 1 = 0$ or $s - \sqrt{2} = 0$.
Thus,$s = \frac{1}{2}$ or $s = \sqrt{2}$.
So,the zeroes of the polynomial are $\frac{1}{2}$ and $\sqrt{2}$.
Verification:
Sum of zeroes $= \frac{1}{2} + \sqrt{2} = \frac{1 + 2\sqrt{2}}{2} = \frac{-[-(1 + 2\sqrt{2})]}{2} = \frac{-(\text{Coefficient of } s)}{\text{Coefficient of } s^{2}}$.
Product of zeroes $= \frac{1}{2} \times \sqrt{2} = \frac{\sqrt{2}}{2} = \frac{1}{\sqrt{2}} = \frac{\text{Constant term}}{\text{Coefficient of } s^{2}}$.
Hence,the relationship between the zeroes and the coefficients is verified.
43
Difficult
Find the zeroes of the following polynomial by the factorisation method and verify the relationship between the zeroes and the coefficients of the polynomial:
$v^{2}+4 \sqrt{3} v-15$

Solution

(A) Let $f(v) = v^{2} + 4 \sqrt{3} v - 15$.
To factorise,we split the middle term: $v^{2} + (5 \sqrt{3} - \sqrt{3}) v - 15 = 0$.
$= v^{2} + 5 \sqrt{3} v - \sqrt{3} v - 15 = 0$.
$= v(v + 5 \sqrt{3}) - \sqrt{3}(v + 5 \sqrt{3}) = 0$.
$= (v + 5 \sqrt{3})(v - \sqrt{3}) = 0$.
Thus,the zeroes are $v = -5 \sqrt{3}$ and $v = \sqrt{3}$.
Verification:
Sum of zeroes $= -5 \sqrt{3} + \sqrt{3} = -4 \sqrt{3} = -\frac{\text{Coefficient of } v}{\text{Coefficient of } v^{2}}$.
Product of zeroes $= (-5 \sqrt{3})(\sqrt{3}) = -5 \times 3 = -15 = \frac{\text{Constant term}}{\text{Coefficient of } v^{2}}$.
Hence,the relationship is verified.
44
Medium
Find the zeroes of the following polynomial by the factorisation method and verify the relationship between the zeroes and the coefficients of the polynomial:
$y^{2}+\frac{3}{2} \sqrt{5} y-5$

Solution

(A) Let $f(y) = y^{2} + \frac{3}{2} \sqrt{5} y - 5$.
To find the zeroes,we set $f(y) = 0$,which implies $y^{2} + \frac{3}{2} \sqrt{5} y - 5 = 0$.
Multiplying by $2$,we get $2y^{2} + 3\sqrt{5}y - 10 = 0$.
Splitting the middle term: $2y^{2} + 4\sqrt{5}y - \sqrt{5}y - 10 = 0$.
$2y(y + 2\sqrt{5}) - \sqrt{5}(y + 2\sqrt{5}) = 0$.
$(y + 2\sqrt{5})(2y - \sqrt{5}) = 0$.
Thus,the zeroes are $y = -2\sqrt{5}$ and $y = \frac{\sqrt{5}}{2}$.
Verification:
Sum of zeroes $= -2\sqrt{5} + \frac{\sqrt{5}}{2} = \frac{-4\sqrt{5} + \sqrt{5}}{2} = -\frac{3\sqrt{5}}{2}$.
From the polynomial $y^{2} + \frac{3}{2} \sqrt{5} y - 5$,the coefficient of $y$ is $\frac{3\sqrt{5}}{2}$ and the coefficient of $y^{2}$ is $1$. Thus,$-\frac{\text{coefficient of } y}{\text{coefficient of } y^{2}} = -\frac{3\sqrt{5}}{2}$.
Product of zeroes $= (-2\sqrt{5}) \times (\frac{\sqrt{5}}{2}) = -5$.
The constant term is $-5$ and the coefficient of $y^{2}$ is $1$. Thus,$\frac{\text{constant term}}{\text{coefficient of } y^{2}} = -5$.
Hence,the relationship is verified.
45
Difficult
Find the zeroes of the following polynomial by the factorisation method and verify the relationship between the zeroes and the coefficients of the polynomial:
$7 y^{2}-\frac{11}{3} y-\frac{2}{3}$

Solution

(A) Let $f(y) = 7y^2 - \frac{11}{3}y - \frac{2}{3}$.
To find the zeroes,set $f(y) = 0$,which implies $\frac{1}{3}(21y^2 - 11y - 2) = 0$,so $21y^2 - 11y - 2 = 0$.
Splitting the middle term: $21y^2 - 14y + 3y - 2 = 0$.
$7y(3y - 2) + 1(3y - 2) = 0$.
$(3y - 2)(7y + 1) = 0$.
Thus,the zeroes are $y = \frac{2}{3}$ and $y = -\frac{1}{7}$.
Verification:
Sum of zeroes = $\frac{2}{3} + (-\frac{1}{7}) = \frac{14 - 3}{21} = \frac{11}{21}$.
From the polynomial $7y^2 - \frac{11}{3}y - \frac{2}{3}$,the coefficient of $y$ is $-\frac{11}{3}$ and the coefficient of $y^2$ is $7$.
Sum of zeroes = $-\frac{\text{coefficient of } y}{\text{coefficient of } y^2} = -\frac{-11/3}{7} = \frac{11}{21}$.
Product of zeroes = $(\frac{2}{3})(-\frac{1}{7}) = -\frac{2}{21}$.
Constant term is $-\frac{2}{3}$,coefficient of $y^2$ is $7$.
Product of zeroes = $\frac{\text{constant term}}{\text{coefficient of } y^2} = \frac{-2/3}{7} = -\frac{2}{21}$.
Hence,the relationship is verified.
46
Medium
Find a quadratic polynomial,the sum and product of whose zeroes are $\sqrt{2}$ and $-\frac{3}{2},$ respectively. Also,find its zeroes.

Solution

(N/A) Let the quadratic polynomial be $p(x) = ax^2 + bx + c$ and its zeroes be $\alpha$ and $\beta$.
Given,sum of zeroes $\alpha + \beta = \sqrt{2}$ and product of zeroes $\alpha \beta = -\frac{3}{2}$.
$A$ quadratic polynomial is given by $k[x^2 - (\alpha + \beta)x + \alpha \beta]$.
Substituting the values,we get $k[x^2 - \sqrt{2}x - \frac{3}{2}]$.
For $k=2$,the polynomial is $2x^2 - 2\sqrt{2}x - 3$.
To find the zeroes,set $2x^2 - 2\sqrt{2}x - 3 = 0$.
$2x^2 - 3\sqrt{2}x + \sqrt{2}x - 3 = 0$.
$\sqrt{2}x(\sqrt{2}x - 3) + 1(\sqrt{2}x - 3) = 0$.
$(\sqrt{2}x + 1)(\sqrt{2}x - 3) = 0$.
Thus,the zeroes are $x = -\frac{1}{\sqrt{2}}$ and $x = \frac{3}{\sqrt{2}}$.
47
Difficult
Verify that the numbers given alongside the cubic polynomials below are their zeroes. Also,verify the relationship between the zeroes and the coefficients in each case: $2x^3 + x^2 - 5x + 2; \frac{1}{2}, 1, -2$.

Solution

(A) Let $p(x) = 2x^3 + x^2 - 5x + 2$.
The given values are $\alpha = \frac{1}{2}, \beta = 1, \gamma = -2$.
First,we verify that these are zeroes:
$p(\frac{1}{2}) = 2(\frac{1}{8}) + \frac{1}{4} - \frac{5}{2} + 2 = \frac{1}{4} + \frac{1}{4} - \frac{5}{2} + 2 = \frac{1}{2} - \frac{5}{2} + 2 = -2 + 2 = 0$.
$p(1) = 2(1)^3 + (1)^2 - 5(1) + 2 = 2 + 1 - 5 + 2 = 0$.
$p(-2) = 2(-8) + 4 - 5(-2) + 2 = -16 + 4 + 10 + 2 = 0$.
Since $p(\frac{1}{2}) = 0, p(1) = 0,$ and $p(-2) = 0$,these are indeed the zeroes.
Comparing $p(x)$ with $ax^3 + bx^2 + cx + d$,we get $a = 2, b = 1, c = -5, d = 2$.
Verification of relationships:
$1$. Sum of zeroes: $\alpha + \beta + \gamma = \frac{1}{2} + 1 - 2 = -\frac{1}{2} = \frac{-b}{a}$.
$2$. Sum of product of zeroes taken two at a time: $\alpha\beta + \beta\gamma + \gamma\alpha = (\frac{1}{2})(1) + (1)(-2) + (-2)(\frac{1}{2}) = \frac{1}{2} - 2 - 1 = \frac{1-6}{2} = -\frac{5}{2} = \frac{c}{a}$.
$3$. Product of zeroes: $\alpha\beta\gamma = (\frac{1}{2})(1)(-2) = -1 = \frac{-d}{a} = \frac{-2}{2} = -1$.
Thus,the relationship is verified.
48
Difficult
Verify that the numbers given alongside the cubic polynomials below are their zeroes. Also,verify the relationship between the zeroes and the coefficients in each case: $x^{3}-4x^{2}+5x-2; 2, 1, 1$.

Solution

(A) Let the polynomial be $p(x) = x^{3} - 4x^{2} + 5x - 2$.
The given numbers are $2, 1, 1$.
For $x = 2$: $p(2) = (2)^{3} - 4(2)^{2} + 5(2) - 2 = 8 - 16 + 10 - 2 = 0$.
For $x = 1$: $p(1) = (1)^{3} - 4(1)^{2} + 5(1) - 2 = 1 - 4 + 5 - 2 = 0$.
Since $p(2) = 0$ and $p(1) = 0$,the numbers $2, 1, 1$ are indeed the zeroes of the polynomial.
Comparing $p(x)$ with the standard form $ax^{3} + bx^{2} + cx + d$,we get $a = 1, b = -4, c = 5, d = -2$.
Verification of relationships:
$1$. Sum of zeroes: $2 + 1 + 1 = 4 = -(-4)/1 = -b/a$.
$2$. Sum of product of zeroes taken two at a time: $(2)(1) + (1)(1) + (2)(1) = 2 + 1 + 2 = 5 = 5/1 = c/a$.
$3$. Product of zeroes: $2 \times 1 \times 1 = 2 = -(-2)/1 = -d/a$.
Thus,the relationship between the zeroes and the coefficients is verified.
49
Medium
Find a cubic polynomial with the sum,sum of the product of its zeroes taken two at a time,and the product of its zeroes as $2, -7, -14$ respectively.

Solution

(A) Let the cubic polynomial be $p(x) = ax^3 + bx^2 + cx + d$ and its zeroes be $\alpha, \beta,$ and $\gamma$.
The relationships between the coefficients and the zeroes are given by:
$1.$ Sum of zeroes: $\alpha + \beta + \gamma = -b/a = 2/1$
$2.$ Sum of the product of zeroes taken two at a time: $\alpha\beta + \beta\gamma + \gamma\alpha = c/a = -7/1$
$3.$ Product of zeroes: $\alpha\beta\gamma = -d/a = -14/1$
Comparing the values,we get $a = 1, b = -2, c = -7,$ and $d = 14$.
Substituting these values into the general form $ax^3 + bx^2 + cx + d$,we get the polynomial:
$p(x) = x^3 - 2x^2 - 7x + 14$.
50
Difficult
If the zeroes of the polynomial $x^{3}-3x^{2}+x+1$ are $a-b, a, a+b$,find $a$ and $b$.

Solution

(A) Given polynomial is $p(x) = x^{3}-3x^{2}+x+1$.
The zeroes are given as $a-b, a, a+b$.
Comparing the polynomial with the standard form $Ax^{3}+Bx^{2}+Cx+D$,we get $A=1, B=-3, C=1, D=1$.
Using the relationship between zeroes and coefficients:
Sum of zeroes $= (a-b) + a + (a+b) = -B/A$.
$3a = -(-3)/1 = 3$.
$a = 1$.
Product of zeroes $= (a-b)(a)(a+b) = -D/A$.
$(1-b)(1)(1+b) = -1/1$.
$1-b^{2} = -1$.
$b^{2} = 2$.
$b = \pm\sqrt{2}$.
Thus,$a=1$ and $b=\pm\sqrt{2}$.

Polynomials — Relationship between Zeroes and Coefficients of a Polynomial · Frequently Asked Questions

1Are these Polynomials questions useful for JEE and NEET?

Yes. All questions in this section are mapped to JEE Main and NEET exam patterns. Previous year questions from JEE Main, NEET, GUJCET and state-level exams are included with full solutions.

2Can I switch to Hindi or Gujarati for these questions?

Yes. Use the language tabs in the hero section or the sidebar to view the same questions and solutions in English, Hindi or Gujarati.

3How do I generate a question paper from this subtopic?

Use the Vedclass Exam Paper Generator — select the chapter and subtopic, set difficulty, and generate Sets A, B, C, D automatically. First 3 chapters of every subject are free.

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D papers from this chapter in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo
For Teachers & Institutes

Generate a Polynomials Exam Paper in 2 Minutes

Select subtopic & difficulty — Sets A, B, C, D auto-generated with No Repeat logic.

First 3 chapters of every subject are free — no payment required.