Calculus

Lesson 6 of 14

Integration by Parts

The product rule in reverse, the LIATE heuristic, and the tabular shortcut.

The formula

Integrate the product rule (uv)′=u′v+uv′(uv)' = u'v + uv' and rearrange:

∫u dv=uv−∫v du\int u\,dv = uv - \int v\,du

You trade one integral for another, which pays off when ∫v du\int v\,du is simpler. Example: ∫xexdx\int x e^x dx. Take u=xu = x, dv=exdxdv = e^x dx, so du=dxdu = dx, v=exv = e^x:

∫xexdx=xex−∫exdx=(x−1)ex+C\int x e^x dx = x e^x - \int e^x dx = (x-1)e^x + C