i have no idea whats going on..please someone explain..it would be great..i get the starting steps but i get lost in the middle...

integrate $\displaystyle 5x^3 / 1 + 16x^4$

what i have so far is...

$\displaystyle Let u = 1 + 16x^4$

$\displaystyle du/dx = 64x^3$

$\displaystyle du = 64x^3 dx$

now what do i do??

i know that it has to be 5/u and then something.....