Calculus Volume Disk

Find the volume of the solid formed by the area of the region bounded by: y=x^2, y=4x-x^2 and rotated around the line y=6

Find the volume of the solid formed by the area of the region bounded by: y=e^{\frac{x}{2}}, y=0, x=0, x=4 and rotated around the x-axis

Rotated about the y-axis.

Find the volume of the solid formed by the area of the region bounded by: y=3, x=4, y=\sqrt[]{x-4} and rotated around the y-axis

What is the volume of this solid of revolution?