MCQ
If $\tan ^{-1} 2 x+\tan ^{-1} 3 x=\frac{\pi}{4}$, then $x=$
  • A
    -1
  • B
    $\frac{1}{3}$
  • $\frac{1}{6}$
  • D
    $\frac{1}{2}$

Answer

Correct option: C.
$\frac{1}{6}$
(c) : We have $\tan ^{-1} 2 x+\tan ^{-1} 3 x=\frac{\pi}{4}$
$
\begin{aligned}
& \Rightarrow \tan ^{-1}\left(\frac{2 x+3 x}{1-2 x \times 3 x}\right)=\frac{\pi}{4} ; x>0 \Rightarrow \frac{5 x}{1-6 x^2}=1 \\
& \Rightarrow 6 x^2+5 x-1=0 \Rightarrow(6 x-1)(x+1)=0 \Rightarrow x=\frac{1}{6}(\because x \neq-1)
\end{aligned}
$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free