How do you integrate int x^3cos(x^2) using integration by parts?

1 Answer
Aug 28, 2016

= 1/2 x^2 sin(x^2) + 1/2cos(x^2) + C

Explanation:

int x^3cos(x^2)

int x^2 . x cos(x^2)

= int x^2 d/dx (1/2 sin(x^2))

ready for IBP
= 1/2 x^2 sin(x^2) - 1/2 int d/dx (x^2) sin(x^2)

= 1/2 x^2 sin(x^2) - int x sin(x^2)

= 1/2 x^2 sin(x^2) - int d/dx ( - 1/2cos(x^2))

= 1/2 x^2 sin(x^2) + 1/2cos(x^2) + C