Put but that won't solve the problem, you need to manage of the other integrals.
I'm having a lot of trouble with this integration. I'm supposed to simplify the integral so that it looks like one of the equations on a table of integrals, which then can be used to find the integral.
Integral of (x^3)*sqrt[(4x^2) -(x^4)]
Now, you can use various methods, but trig sub is an option.
You can look at the tables or try to do it yourself.
Make the sub
See?. You can break it all up into easier integrals and go from there.
Of course, as I said, this is one way.