Integral Calculus Question 350

Question: The value of $ \int{\frac{\log x}{{{(x+1)}^{2}}}dx} $ is

[UPSEAT 1999]

Options:

A) $ \frac{-\log x}{x+1}+\log x-\log ,(x+1) $

B) $ \frac{\log x}{( x+1 )}+\log x-\log ,(x+1) $

C) $ \frac{\log x}{x+1}-\log x-\log ,(x+1) $

D) $ \frac{-\log x}{x+1}-\log x-\log ,(x+1) $

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Answer:

Correct Answer: A

Solution:

$ \int{\frac{\log x}{{{(x+1)}^{2}}}dx=\int{\log x,{{(x+1)}^{-2}}}}dx $ $ =\log x.{ -{{(x+1)}^{-1}} } $ $ -\int{\frac{1}{x}.{-{{(x+1)}^{-1}}}dx} $ $ =\frac{-\log x}{(x+1)}+\int{\frac{1}{x(x+1)}dx} $ $ =\frac{-\log x}{(x+1)}+\int{[ \frac{1}{x}-\frac{1}{x+1} ]dx} $ $ =\frac{-\log x}{x+1}+\log x-\log (x+1) $ .