Let I=∫01x31−x2dxI = \int_{0}^{1} \frac{x^3}{\sqrt{1-x^2}} dxI=∫011−x2x3dx. Which substitution is most effective for solving this integral?
u=x2u = x^2u=x2
u=x3u = x^3u=x3
x=sin(θ)x = \sin(\theta)x=sin(θ)
x=tan(θ)x = \tan(\theta)x=tan(θ)