Question

resolva a integral usando a integração por partes 

Answer 1

u=x/3  du=1/3dx  dv=senxdx  v=-cosx

$\int\limits^a_b { \frac{1}{3} xsenx} \, dx= -\frac{x}{3} cosx+\frac{1}{3} \int\limits^a_b {cosx} \, dx \\ -\frac{x}{3} cosx+\frac{1}{3} cosx =\frac{1}{3}(senx-xcosx) + C$ 

E