i got this problem from my lecture,
1. integral equation, i need to know step by step to got the answer
$\int y^3 \sin(2x) dx$
my friends said the answer is $-y^3 \cos^2(x)$, but i don't know how to get this.
differential equation,
a. $\frac{Dm}{dy} (3y^2 + y \sin (2xy))$
b. $\frac{Dn}{dx}( 6xy + x \sin (2xy))$
my friend said again two of them have same answer, it said 6y + sin 2xy + 2xy cos 2xy
but once again i don't know how to get thia,someone can tell me step by step please, i really appreciate it, thanks a lot.