hi guys can you please help me with this:

If f(x)= cos^4(x)sin(x), evaluate$\displaystyle \int_0^\pi \! f(t) \, \mathrm{d}t.$

Would this be correct:

u=cos(x)

du=-sin(x)dx

-$\displaystyle \int_0^\pi \! u^4 \, \mathrm{d}u$

cos(0)=1, cos(pi)=-1

$\displaystyle -[\frac{u^5}{5}]^{-1}_{1} $

Is there a problem that it's decreasing from a to b? Do I need to switch something before I do F(b)-F(a)?