For L.P.P, maximize $z=4 x_1+2 x_2$ subject to $3 x_1+2 x_2 \geq 9, x_1-x_2 \leq 3, x_1 \geq 0, x_2 \geq 0$ has

The function $f(x)=x^3-3 x$ is ............

If $x=\sin \theta, y=\sin ^3 \theta$ then $\frac{d^2 y}{d x^2}$ at $\theta=\frac{\pi}{2}$ is ............

The area of the region enclosed between pair of the lines $x y=0$ and the lines $x y+5 x-4 y-20=0$, is .............