Differentiation Question 236

Question: If $ y={{\tan }^{-1}}( \frac{{x^{1/3}}+{a^{1/3}}}{1-{x^{1/3}}{a^{1/3}}} ) $ , then $ \frac{dy}{dx}= $

[DSSE 1986]

Options:

A) $ \frac{1}{3{x^{2/3}}(1+{x^{2/3}})} $

B) $ \frac{1}{3{x^{2/3}}(1+{x^{2/3}})} $

C) $ -\frac{1}{3{x^{2/3}}(1+{x^{2/3}})} $

D) $ -\frac{a}{3{x^{2/3}}(1+{x^{2/3}})} $

Show Answer

Answer:

Correct Answer: A

Solution:

$ y={{\tan }^{-1}}( \frac{{x^{1/3}}+{a^{1/3}}}{1-{x^{1/3}}.{a^{1/3}}} )={{\tan }^{-1}}({x^{1/3}})+{{\tan }^{-1}}{a^{1/3}} $

Therefore $ \frac{dy}{dx}=\frac{1}{3{x^{2/3}}(1+{x^{2/3}})} $ .