• July 18th 2010, 06:45 PM
racewithferrari
I don't see anything wrong with it. Once you do the u-substitution $u=\sqrt{x}$ to obtain $50\int sin^3(u)du$ it's obviously just a matter of integrating $sin^3(u)du$ which can be done using the reduction formula for powers of sine. The integral calculator used the correct formula. Perhaps you forgot to include the constant of integration?
$\frac{50}{3} \left[ \cos^3(\sqrt{x} ) - 3 \cos(\sqrt{x} ) \right] + C$