Differentiation Question 393

Question: If $ y=\sqrt{(1-x)(1+x)} $ , then

Options:

A) $ (1-x^{2})\frac{dy}{dx}-xy=0 $

B) $ (1-x^{2})\frac{dy}{dx}+xy=0 $

C) $ (1-x^{2})\frac{dy}{dx}-2xy=0 $

D) $ (1-x^{2})\frac{dy}{dx}+2xy=0 $

Show Answer

Answer:

Correct Answer: B

Solution:

$ y^{2}=(1-x^{2}) $

Therefore $ 2y\frac{dy}{dx}=-2x $ or $ \frac{dy}{dx}=\frac{-x}{y}=\frac{-xy}{(1-x^{2})} $

or $ (1-x^{2})\frac{dy}{dx}+xy=0 $ .