Question:
Mark (√) against the correct answer in the following:
Let $f: Q \rightarrow Q: f(x)=(2 x+3) .$ Then, $f^{-1}(y)=?$
A. $(2 y-3)$
B. $\frac{1}{(2 \mathrm{y}-3)}$
C. $\frac{1}{2}(\mathrm{y}-3)$
D. none of these
Solution:
$f(x)=2 x+3$
$\Rightarrow y=2 x+3$
$x \Longleftrightarrow y$
$\Rightarrow x=2 y+3$
$\Rightarrow x-3=2 y$
$\Rightarrow \frac{x-3}{2}=y$
$x \Longleftrightarrow y$
$\Rightarrow \frac{y-3}{2}=x$
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