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Let tan⁡−1y=tan⁡−1x+tan⁡−1(2x1−x2)\tan^{-1}y = \tan^{-1}x + \tan^{-1}\left(\frac{2x}{1-x^2}\right). Then yy is :

Solution

✅ Correct Option: 1

Since tan⁡−1(2x1−x2)=2tan⁡−1x\tan^{-1}\left(\frac{2x}{1-x^2}\right) = 2\tan^{-1}x:

tan⁡−1y=3tan⁡−1x\tan^{-1}y = 3\tan^{-1}x, so y=tan⁡(3θ)y = \tan(3\theta) where θ=tan⁡−1x\theta = \tan^{-1}x.

y=3tan⁡θ−tan⁡3θ1−3tan⁡2θ=3x−x31−3x2y = \frac{3\tan\theta - \tan^3\theta}{1 - 3\tan^2\theta} = \frac{3x - x^3}{1 - 3x^2}.

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