Integral Calculus Question 153

Question: $ \int_{{}}^{{}}{{{\tan }^{-1}}xdx=} $

[Roorkee 1977]

Options:

A) $ x{{\tan }^{-1}}x+\frac{1}{2}\log (1+x^{2}) $

B) $ x{{\tan }^{-1}}x-\frac{1}{2}\log (1+x^{2}) $

C) $ (x-1){{\tan }^{-1}}x $

D) $ x{{\tan }^{-1}}x-\log (1+x^{2}) $

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Answer:

Correct Answer: B

Solution:

$ \int_{{}}^{{}}{{{\tan }^{-1}}x dx}=x{{\tan }^{-1}}x-\int_{{}}^{{}}{\frac{x}{1+x^{2}} dx+c} $ $ =x{{\tan }^{-1}}x-\frac{1}{2}\log (1+x^{2})+c. $ Note : Students should remember this question as a formula.