Question: Mark $(\sqrt{)}$ against the correct answer in the following:
If $y=\sin ^{-1}\left(3 x-4 x^{3}\right)$ then $\frac{d y}{d x}=?$
A. $\frac{3}{\sqrt{1-x^{2}}}$
B. $\frac{-4}{\sqrt{1-x^{2}}}$
C. $\frac{3}{\sqrt{1+\mathrm{x}^{2}}}$
D. none of these
Solution:
