Consider the given integral.
I=∫xe2xdx
We know that
∫uvdx=u∫vdx−∫(d(u)dx∫vdx)dx
Therefore,
I=x(e2x2)−∫1(e2x2)dx
I=xe2x2−12∫e2xdx
I=xe2x2−12(e2x2)+C
I=xe2x2−e2x4+C
I=e2x(2x−1)4+C