Question:
If $f: R \rightarrow R$ is defined by $f(x)=10 x-7$, then write $f^{-1}(x)$.
Solution:
Let $f^{-1}(x)=y$ $\ldots(1)$\
$\Rightarrow f(y)=x$
$\Rightarrow 10 y-7=x$
$\Rightarrow 10 y=x+7$
$\Rightarrow y=\frac{x+7}{10}$
$\Rightarrow f^{-1}(x)=\frac{x+7}{10}$ (From (1)