If $y(x)$ is the solution of the differential equation $(x + 2)\frac{dy}{dx} = x^2 + 4x - 9, x \ne -2$ and $y(0) = 0$,then $y(-4)$ is equal to

If a polygon of $n$ sides has $275$ diagonals,then $n$ is equal to

The number of possible straight lines passing through $(2, 3)$ and forming a triangle with the coordinate axes,whose area is $12 \, sq. \, units$,is

$A$ converging beam of rays is incident on a diverging lens. Having passed through the lens,the rays intersect at a point $15 \, cm$ from the lens on the opposite side. If the lens is removed,the point where the rays meet will move $5 \, cm$ closer to the lens. The focal length of the lens is.....$cm$

If we remove half of the forest cover of the Earth,the crisis that will occur is:

The dependence of disturbances due to two waves on time is shown in the figure. The ratio of their intensities $I_1 / I_2$ will be