Mathematics

Evaluate the following definite integral:
$$\displaystyle \int_{-1}^{1}\dfrac {1}{x^2 +2x+5}dx$$


SOLUTION
Consider, $$I=\displaystyle \int_{-1}^1\dfrac {1}{x^2+2x+5}dx$$

$$I =\displaystyle \int_{-1}^1\dfrac {1}{(x+1)^2 +2^2}dx$$

$$I=\dfrac {1}{2}\left [\tan^{-1} \dfrac {x+1}{2}\right]_{1-}^1 $$

$$I=\dfrac {1}{2}(\tan^{-1} 1-\tan^{-1}0)$$

$$I=\dfrac {\pi}{8}$$

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Subjective Medium Published on 17th 09, 2020
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