Mathematics

Problem

The derivative of

\tan^{-1}\left(\frac{\sqrt{1+x^2}-1}{x}\right)

with respect to

\tan^{-1}\left(\frac{2x\sqrt{1-x^2}}{1-2x^2}\right)

x = 0

is (a)

1/8

(b)

1/4

(c)

1/2

(d) 1