Which of the following integrals can be best evaluated using integration by parts?

a. ∫ xsin(x²) dx
b. ∫ x²sin(x) dx
c. ∫ sin²(x) dx

A) can be done using u-substitution Let u = x^2, du = 2x dx

C) can be done using trig identity ... cos(2x) = 1 - 2sin^2

B) can only be done using integration by parts. It is a product of 2 distinct functions and a u-sub does not simplify the integral.