The family in which many plants are $C_4$ type is:

The equation of the pair of lines joining the origin to the points of intersection of $x^2+y^2=9$ and $x+y=3$ is:

The variance of $20$ observations is $5$. If each observation is multiplied by $2$,then the new variance of the resulting observations is:

If $(a+bx)^{-3} = \frac{1}{27} + \frac{1}{3}x + \dots$,then the ordered pair $(a, b)$ equals to

Let $f(x)$ be a polynomial of degree $3$ such that $f(-1) = 10$,$f(1) = -6$,$f(x)$ has a critical point at $x = -1$,and $f'(x)$ has a critical point at $x = 1$. Then $f(x)$ has a local minima at $x =$

Three identical bodies of equal mass $M$ each are moving along a circle of radius $R$ under the action of their mutual gravitational attraction. The speed of each body is