The indefinite integral of x^3sq root of x^2+1. I have no idea where to even start. I'm guessing I'd have to use substitution of some sort to find this antiderivative but I don't know how the square root would come into play. I know I could use x^3 as u and du would then be 3x^2 so it'd be 1/3 the integral of the square root of 1 which is just as complicated.