I cannot seem to get this correct Please help Evaluate the i

I cannot seem to get this correct. Please help.

Evaluate the indefinite integral by using the given substitution to reduce the integral to standard form.

Solution

u = 6 - r^3 du = -3r^2dr => -2du = 6r^2dr so , our integral becomes = integral ( -2du/sqrt(u)) = -2*integral( u^-(1/2) )du = -2* ( u^(1/2) / (1/2) ) = -4*sqrt(u) + C = -4*sqrt(6 - r^3) + C