Considering only the Principal values of inverse function, the set $\left\{x \geq 0 / \tan ^{-1}(2 x)+\tan…
Considering only the Principal values of inverse function, the set
$\left\{x \geq 0 / \tan ^{-1}(2 x)+\tan ^{-1} 3 x=\frac{\pi}{4}\right\}$
- is a singleton set.
- contains more than two elements.
- contains two elements.
- is an empty set.
Solution
$\begin{aligned} & \tan ^{-1}(2 x)+\tan ^{-1}(3 x)=\frac{\pi}{4} \\ & \Rightarrow \tan ^{-1} \frac{2 x+3 x}{1-2 x \times 3 x}=\tan ^{-1}(1) \\ & \Rightarrow \frac{5 x}{1-6 x^2}=1 \\ & \Rightarrow 5 x=1-6 x^2 \\ & \Rightarrow 6 x^2+5 x-1=0 \\ & \Rightarrow(x+1)(6 x-1)=0\end{aligned}$
$\Rightarrow x=-1$ or $x=\frac{1}{6}$
But $x \geq 0$
Hence $x=\frac{1}{6}$ (only) i.e., single ton set
Asked in: MHT CET 2022 (05 Aug Shift 1)
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