Hey guys:

Had one problem with my math homework:

$\displaystyle \int \frac{y^2}{25+y^2} dy$

So I tried $\displaystyle y=5\tan x$

So then: $\displaystyle dy=5\sec^2xdx$,

So the integration appears as: $\displaystyle \int \frac{25\tan^2x}{25(1+\tan^2x)}(5\sec^2x)dx$

Which simplifies to: $\displaystyle \int 5\tan^2x dx$, which is where I get stuck.

Any advice on moving forward, or a different, easier method?

Peter