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Question: Answered & Verified by Expert
If $f: \mathbb{R} \rightarrow \mathbb{R}$ is defined by $f(x)=3 x-4$, then $f^{-1}: \mathbb{R} \rightarrow \mathbb{R}$ is
MathematicsFunctionsJEE Main
Options:
  • A $4-3 x$
  • B $\frac{x+4}{3}$
  • C $\frac{1}{3 x-4}$
  • D $\frac{3}{x+4}$
Solution:
2609 Upvotes Verified Answer
The correct answer is: $\frac{x+4}{3}$
$\begin{aligned} & \text { Given } f(x)=3 x-4 \text {. Now let } y=f^{-1}(x) \Rightarrow f(y)=x \\ & \Rightarrow 3 y-4=x \Rightarrow 3 y=x+4 \\ & \Rightarrow y=\frac{x+4}{3} \Rightarrow f^{-1}(x)=\frac{x+4}{3}\end{aligned}$

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