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If the function $( f : R \rightarrow R )$ is given by $( f(x) =\large \frac{x+3}{2} )$ and $( g : R \rightarrow R)$ is given by $( g(x)=2x-3,)$ find (i) fog and (ii) gof. Is $( f^{-1}=g)$?

1 Answer

Step 1:
Step 2:
$\therefore fog=gof$
Step 3:
Now let us find $f^{-1}$
Let $f(x)=y$
$\Rightarrow \large\frac{x+3}{2}=$$y$
Clearly $2y-3\in R$ for all $y\in R$
Step 4:
Thus for all $y\in R$ there exists $x=\large\frac{y+7}{3}$$\in R$
Such that $f(x)=f(2y-3)$
$\Rightarrow \large\frac{2y-3+3}{2}$
$\Rightarrow y$
$\therefore f^{-1}(y)=2y-3$
$\therefore f^{-1}:R\rightarrow R$ is given by
Which is $g(x)$
$\therefore f^{-1}(x)=g(x)$
answered Oct 1, 2013 by sreemathi.v

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