CAPE Pure Mathematics Unit 2 · May/June 2017 · Paper 1 · Question Q6

Given that y = \tan^{-1}(2x), then \frac{dx}{dy} equals

1. (A)\frac{1}{\sqrt{1 - (2x)^2}}
2. (B)\frac{1}{\sqrt{1 - x^2}}
3. (C)\frac{2}{1 + 4x^2}
4. (D)\frac{1 + 4x^2}{2}