- #1

- 32

- 0

## Homework Statement

Im looking over the notes in my lecture and the prof wrote,

[tex] \int_{0}^{2} \pi(4x^2-x^4)dx=\frac{64\pi}{15} [/tex]

Im wondering whats the indefinite integral of this equation.

## Homework Equations

using u substitution

## The Attempt at a Solution

[tex] \int \pi(4x^2-x^4)dx= \pi \int x^2(4-x^2)dx \\

u = 4 - x^2 \ \ \ \ \ \ \ \ \ \

-\frac {1}{2} du =xdx \\

[/tex]

Im confuse since i have an x^2 but my du=x.

I attempted to also use from u to get,

[tex]

x=\sqrt{4-u} \\

\pi \int \frac{1}{2}u\sqrt{4-u}dx

[/tex]

but it seems this made the formula harder to integrate...or am i just giving up too quickly