I took these questions out of my book to review. I am stuck on volume of solids.

Find the volume of the solid generated by revolving the shaded region around the x-axis.

1.About the x axis

y = 4 sec x

2. y = (x)^.5, y = 0, x=0, x=6

3. y= 1/x, y=0, x=1, x=5