Evaluate the integral using u substitution.

Integral of (cos(x))^25 sin(x) dx; use u = cos(x)

I obtained (cos(x))^26/26. However, there is a negative in the solution and I am unsure of how there is a negative.

Unless since u = cos x, and you plug in du, then do you do the derivative of sin and get - cos which results int he negative?