Rationalise the denominator in each of the following:
$\frac{1}{7-4 \sqrt{3}}$
$\frac{1}{7-4 \sqrt{3}}$
(A) To rationalise the denominator of $\frac{1}{7-4 \sqrt{3}}$,we multiply the numerator and the denominator by the conjugate of the denominator,which is $7+4 \sqrt{3}$.
$\frac{1}{7-4 \sqrt{3}} \times \frac{7+4 \sqrt{3}}{7+4 \sqrt{3}} = \frac{7+4 \sqrt{3}}{(7)^2 - (4 \sqrt{3})^2}$
$= \frac{7+4 \sqrt{3}}{49 - (16 \times 3)}$
$= \frac{7+4 \sqrt{3}}{49 - 48}$
$= \frac{7+4 \sqrt{3}}{1}$
$= 7+4 \sqrt{3}$
$\frac{1}{7-4 \sqrt{3}} \times \frac{7+4 \sqrt{3}}{7+4 \sqrt{3}} = \frac{7+4 \sqrt{3}}{(7)^2 - (4 \sqrt{3})^2}$
$= \frac{7+4 \sqrt{3}}{49 - (16 \times 3)}$
$= \frac{7+4 \sqrt{3}}{49 - 48}$
$= \frac{7+4 \sqrt{3}}{1}$
$= 7+4 \sqrt{3}$
Explore More
Similar Questions
Multiply $3 \sqrt{7}$ and $5 \sqrt{7}$.
Easy
View SolutionRationalise the denominator of the following number:
$\frac{1}{5+2 \sqrt{3}}$
$\frac{1}{5+2 \sqrt{3}}$
Medium
View SolutionClassify the following numbers as rational or irrational:
$(i)$ $2-\sqrt{5}$
$(ii)$ $(3+\sqrt{23})-\sqrt{23}$
$(iii)$ $\frac{2 \sqrt{7}}{7 \sqrt{7}}$
$(iv)$ $\frac{1}{\sqrt{2}}$
$(v)$ $2 \pi$
$(i)$ $2-\sqrt{5}$
$(ii)$ $(3+\sqrt{23})-\sqrt{23}$
$(iii)$ $\frac{2 \sqrt{7}}{7 \sqrt{7}}$
$(iv)$ $\frac{1}{\sqrt{2}}$
$(v)$ $2 \pi$
Medium
View SolutionIf $x=\frac{\sqrt{3}+\sqrt{2}}{\sqrt{3}-\sqrt{2}}$ and $y=\frac{\sqrt{3}-\sqrt{2}}{\sqrt{3}+\sqrt{2}},$ then find the value of $x^{2}+y^{2}$.
Medium
View SolutionIf $\sqrt{5} = 2.236$,then evaluate $\frac{4 - \sqrt{5}}{\sqrt{5}}$ correct to four decimal places.
Medium
View SolutionVedclass Products
For Students
Vedclass Test Series
Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.
Start Free TrialFor Teachers
Exam Paper Generator
Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.
Try FreeFor Institutes
Online Exam Module
Live online exams with unlimited students, 360° analytics & white-label branding.
See Demo