2. Assume that the function f has an inverse. a) Show that f(x)dx = fy f'(y)dy. (Hint: use the substitution y = f-1(x)) b) Using integration by parts on the second integral in (a), show that: ff-1(x)dxfy f'(y)dy = xf-1(x)- ff(y)dy = c) Use the formula obtained in (b) to evaluate: J tan¹x dx.