Differentiation Question 350

Question: $ \frac{d}{dx}{{\tan }^{-1}}( \frac{ax-b}{bx+a} )= $

Options:

A) $ \frac{1}{1+x^{2}}-\frac{a^{2}}{a^{2}+b^{2}} $

B) $ \frac{-1}{1+x^{2}}-\frac{a^{2}}{a^{2}+b^{2}} $

C) $ \frac{1}{1+x^{2}}+\frac{a^{2}}{a^{2}+b^{2}} $

D) None of these

Show Answer

Answer:

Correct Answer: D

Solution:

$ \frac{d}{dx}{{\tan }^{-1}}( \frac{ax-b}{bx+a} )=\frac{1}{1+{{( \frac{ax-b}{bx+a} )}^{2}}}. $

$ \frac{d}{dx}( \frac{ax-b}{bx+a} ) $

$ =\frac{a^{2}+b^{2}}{a^{2}+b^{2}+a^{2}x^{2}+b^{2}x^{2}}=\frac{1}{1+x^{2}} $ .