How do you find the antiderivative of int sinx(cosx)^(3/2) dxsinx(cosx)32dx?

1 Answer
Jan 14, 2017

-2/5(cosx)^(5/2)+C25(cosx)52+C

Explanation:

Since we don't want to have to deal with the 3//23/2 power, let u=cosxu=cosx. This implies that du=-sinxcolor(white).dxdu=sinx.dx.

So, we need to modify our integral just a little:

intsinx(cosx)^(3/2)dx=-int(cosx)^(3/2)(-sinxcolor(white).dx)=-intu^(3/2)color(white).dusinx(cosx)32dx=(cosx)32(sinx.dx)=u32.du

Integrate this using the rule intu^ncolor(white).du=u^(n+1)/(n+1)un.du=un+1n+1, where n!=-1n1.

=-u^(5/2)/(5/2)=-2/5u^(5/2)=-2/5(cosx)^(5/2)+C=u5252=25u52=25(cosx)52+C