Integral Calculus Question 169

Question: $ \int{x^{51}({{\tan }^{-1}}x+{{\cot }^{-1}}x)dx} $

Options:

A) $ \frac{x^{52}}{52}({{\tan }^{-1}}x+{{\cot }^{-1}}x)+c $

B) $ \frac{x^{52}}{52}({{\tan }^{-1}}x-{{\cot }^{-1}}x)+c $

C) $ \frac{\pi x^{52}}{104}+\frac{\pi }{2}+c $

D) $ \frac{x^{52}}{52}+\frac{\pi }{2}+c $

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Answer:

Correct Answer: A

Solution:

[a] $ \int{x^{51}({{\tan }^{-1}}x+{{\cot }^{-1}}x)dx} $ $ =\int{x^{51}.\frac{\pi }{2}dx{ \therefore {{\tan }^{-1}}x+{{\cot }^{-1}}x=\frac{\pi }{2} }} $ $ =\frac{\pi x^{52}}{104}+c=\frac{x^{52}}{52}({{\tan }^{-1}}x+{{\cot }^{-1}}x)+c $ .