Chapter 11.1, Problem 15E

In each of Problems 13-18, find the derivative of the function in part (a). Then find the derivative of the function in part (b) or show that the function in part (b) is the same function as that in part (a).

(a) $y=\frac{1}{3}\ln \left(x^2-1\right)$

(b) $y=\ln \sqrt[3]{x^2-1}$