If $\tan ^{-1} x=\frac{\pi}{4}-\tan ^{-1}\left(\frac{1}{3}\right)$, then $x$ is

If $\tan ^{-1} x=\frac{\pi}{4}-\tan ^{-1}\left(\frac{1}{3}\right)$, then $x$ is
  1. $\frac{1}{3}$
  2. $\frac{1}{2}$
  3. $\frac{1}{4}$
  4. $\frac{1}{6}$

Solution

Given equation $\tan ^{-1} x=\frac{\pi}{4}-\tan ^{-1}\left(\frac{1}{3}\right)$ $\begin{aligned} &\Rightarrow \tan ^{-1} x=\tan ^{-1}(1)-\tan ^{-1}\left(\frac{1}{3}\right) \\ &\left.\Rightarrow \quad \tan ^{-1} x=\tan ^{-1}\left(\frac{1-\frac{\pi}{3}}{1+\frac{1}{3}}\right) \tan ^{-1}(1)\right) \\ &\Rightarrow \quad\left[\because \tan ^{-1} x-\tan ^{-1} y=\tan ^{-1}\left(\frac{x-y}{1+x y}\right)\right] \\ &\Rightarrow \quad \tan ^{-1} x=\tan ^{-1}\left(\frac{2 / 3}{4 / 3}\right) \\ &\Rightarrow \quad x=1 / 2 \end{aligned}$

Asked in: TEST SERIES MHT-CET Full Test 6

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