Question: Shells/ washers/disks

Consider the solid obtained by rotating the region bounded by the given curves about the x-axis.

1)

y=1-25x^2, and y=0

Find the volume V of this solid.
Sketch the region, the solid, and a typical disk or washer.

2)

Use the method of cylindrical shells to find the volume V generated by rotating the region bounded by the given curves about the y-axis.

Sketch the region and a typical shell.

Use the method of cylindrical shells to find the volume V of the solid obtained by rotating the region bounded by the given curves about the x-axis.
Sketch the region and a typical shell.

4)

The region bounded by the given curves is rotated about the y-axis.

Find the volume V of the resulting solid by any method.

I keep getting wrong algebra for these problems, and they are not in the back of the nook. could you please let me know what the answer is for each of these?

thank you!