If a curve $y=a \sqrt{x}+b x$ passes through the point $(1,2)$ and the area bounded by this curve, line $x=4$ and the X -axis is 8 sq . units, then the value of $a-b$ is

The area bounded by the curve $x=2-y-y^2$ and the Y -axis is

The area of the region bounded by the curve $y=|x-2|$ between $x=1, x=3$ and X -axis is ……

The area inside the parabola $y^2=4 \mathrm{a} x$, between the lines $x=\mathrm{a}$ and $x=4 \mathrm{a}$ is equal to