∫x2ex3cos(ex3)dx=
3sin(ex3)+C
sin(ex3)+C
13sin(ex3)+C
−13sin(ex3)+C
∫x2ex3cos(ex3)dx, put ex3=t ⇒ex3.3x2=dtdx
=13∫3x2ex3cos(ex3)dx=13∫costdt
=13(sint)+C.