\(\int_{0}^{1}\displaystyle \tan^{-1}\left(\frac{2x-1}{1+x-x^2}\right) dx\) is equal to
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 0
Let I be the integral. By the property \(\int_{0}^{a} f(x)\,dx = \int_{0}^{a} f(a - x)\,dx\) with a = 1, x is replaced by 1 − x:
\(2(1 - x) - 1 = 1 - 2x\)
\(1 + (1 - x) - (1 - x)^2 = 1 + x - x^2\)
So the numerator changes sign and the denominator is unchanged:
\( \displaystyle I = \int_{0}^{1} \tan^{-1}\left(\frac{1 - 2x}{1 + x - x^2}\right) dx \)
Since \(\tan^{-1}(-t) = -\tan^{-1}t\) (odd function):
\( \displaystyle I = -\int_{0}^{1} \tan^{-1}\left(\frac{2x - 1}{1 + x - x^2}\right) dx = -I \)
\(2I = 0,\quad I = 0\)