The area of the region (in sq.units) bounded by the curve $y = 2\sqrt{1 - x^2}$ and the X-axis is _____

If $\dfrac{dy}{dx} = y + 5$ and $y(0) = 4$ then $y(\log 2)$ is equal to

The solution of the differential equation $\dfrac{dy}{dx} = \dfrac{x+y}{x-y}$ is

A spherical balloon expands at a rate proportional to its surface area. Initially its radius is 2 cm and 5 minutes later it increases upto 7 cm, then surface area of spherical balloon after 12 minutes will be