# Homework Help: Relation with counting volume of a solid revolution

1. Jan 7, 2010

### b00tofuu

1. The problem statement, all variables and given/known data

let f(x)=x^3+x^5. Evaluate int((f(x)^-1)^2, x = 0 .. 2)

3. The attempt at a solution
i have a feeling that it has a relation with counting volume of a solid revolution.but i don't know how to answer it...

2. Jan 7, 2010

### tiny-tim

Hi b00tofuu!

(try using the X2 tag just above the Reply box )
Do you mean ∫02 1/(x3 + x5)2 dx ?

If so, factor it, and then use partial fractions.

3. Jan 7, 2010

### b00tofuu

Re: integral

no, it's not what i meant...
its the squared of the inverse function of (x^3+x^5).
a.the question first asked about the volume of solid revolution of a function y=f(x) bounded by y=b, and the y axis. the function crossed (0,0),(a,b) where a>0. i'vc got the answer
int(phi(f(y)^-1)^2, y = 0 .. b) by the disk method.
then the second point of the question is where i have the problem
b. let f(x)=x^3+x^5. Evaluate int((f(x)^-1)^2, x = 0 .. 2)

i think it's related to each other... but dunno...

4. Jan 7, 2010