Verify the formula using any method.

for .

*Proof.* First, we integrate by parts with

This gives us,

Now, we bring the back over to the left (since this integral is the same one we started with) and have

This was the requested integral formula

Indefinite integral of a continuous f is also primitive of f (page 211). That can be used in these exercises to validate the equality, maybe in a more straightforward way.