Volume of Solid: Find Y-Axis Rot. Region

[africanmasks]

Homework Statement

Find the volume of the solid formed by rotating the region enclosed by the following equations about the Y-AXIS.

y= e^(3x)+5
y=0
x=0
x= 1/2

Homework Equations

The Attempt at a Solution

I keep getting the answer wrong. I broke the problem into two parts: solved a cylinder(disk) from y= 0 to 5 and solved a washer from y=5 to e^(3/2)+5

My answer was (1.25pi) (for cylinder or disk) + (.49811372pi) (for washer)

 

[LCKurtz]

Where's your work? For the cylinder wouldn't x go from 0 to 1/2?

 

[africanmasks]

you're rotating around the y not x

 

[LCKurtz]

you're rotating around the y not x

Yes, so the cylinder elements are parallel to the y axis, sometimes called "dx elements". Your natural variable for that is x.

Maybe I misunderstand your terminology. Is what you call a cylinder what some texts call a shell?