Functions Question 57
Question: If $ f:IR\to IR $ is defined by $ f(x)=3x-4 $ , then $ {f^{-1}}:IR\to IR $ is
[SCRA 1996]
Options:
A) $ 4-3x $
B) $ \frac{x+4}{3} $
C) $ \frac{1}{3x-4} $
D) $ \frac{3}{x+4} $
Show Answer
Answer:
Correct Answer: B
Solution:
Given $ f(x)=3x-4 $ . Now let $ y={f^{-1}}(x)\Rightarrow f(y)=x $
$ \Rightarrow 3y-4=x\Rightarrow 3y=x+4 $
$ \Rightarrow y=\frac{x+4}{3}\Rightarrow {f^{-1}}(x)=\frac{x+4}{3} $ .
BETA
