Definite Integration Question 131

Question: $ \int _{-1}^{0}{\frac{dx}{x^{2}+2x+2}=} $

[MP PET 2000]

Options:

A) 0

B) $ \pi /4 $

C) $ \pi /2 $

D) $ -\pi /4 $

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Answer:

Correct Answer: B

Solution:

$ I=\int _{-1}^{0}{\frac{dx}{x^{2}+2x+2}} $

$ =\int _{-1}^{0}{\frac{dx}{{{(x+1)}^{2}}+1}} $

$ =[{{\tan }^{-1}}(x+1)] _{-1}^{0} $

$ =[{{\tan }^{-1}}1-{{\tan }^{-1}}0]=\frac{\pi }{4} $ .