Which substitution best simplifies ∫1xx2−1dx\int \frac{1}{x \sqrt{x^2 - 1}} dx∫xx2−11dx?
u=x2u = x^2u=x2
u=x2−1u = \sqrt{x^2 - 1}u=x2−1
x=sinθx = \sin \thetax=sinθ
x=tanθx = \tan \thetax=tanθ