$\int_{0}^{1} \tan ^{-1}\left(\frac{2 x-1}{1+x-x^{2}}\right) d x=$

$\int_{0}^{1} \tan ^{-1}\left(\frac{2 x-1}{1+x-x^{2}}\right) d x=$
  1. 1
  2. 4
  3. 2
  4. 0

Solution

$\int_{0}^{1} \tan ^{-1}\left(\frac{2 x-1}{1+x-x^{2}}\right) d x$ $=\int_{0}^{1} \tan ^{-1}\left[\frac{x-(1-x)}{1+x(1-x)}\right] d x=\int_{0}^{1}\left[\tan ^{-1} x-\tan ^{-1}(1-x)\right] d x$...(1) $=\int_{0}^{1}\left[\tan ^{-1}(1-x)-\tan ^{-1}(1-(1-x))\right] d x=\int_{0}^{1}\left[\tan ^{-1}(1-x)-\tan ^{-1}(x)\right] d x$...(2) Adding (1) \& (2), we get $2 I=0 \Rightarrow I=0$

Asked in: MHT CET 2020 (19 Oct Shift 2)

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