Question

打勾的题怎么做，要具体过程

Answer 1

∫ x²sinx dx
=-∫ x² dcosx
=-(x²cosx-∫ cosx dx²)
=-x²cosx+2∫ xcosx dx
=-x²cosx+2∫ x dsinx
=-x²cosx+2(xsinx-∫ sinx dx)
=-x²cosx+2xsinx+2cosx+C