MCQ
Let $\text{f}:\text{R}-\Big\{\frac{3}{5}\Big\}\rightarrow\ \text{R}$ be defined by $\text{f(x)}=\frac{3\text{x}+2}{5\text{x}-3}.$ Then,
  • $f^{-1}(x)=f(x)$
  • B
    $f^{-1}(x)=-f(x)$
  • C
    $f \circ f(x)=-x$
  • D
    $\text{f}^{-1}(\text{x})=\frac{1}{19}\text{f(x)}$

Answer

Correct option: A.
$f^{-1}(x)=f(x)$
Given function is $\text{f}:\text{R}-\Big\{\frac{3}{5}\Big\}\rightarrow\ \text{R}$ be defined by $\text{f(x)}=\frac{3\text{x}+2}{5\text{x}-3}$
fo $f(x) = f(f(x))$
$=\text{f}\Big(\frac{3\text{x}+2}{5\text{x}-3}\Big)$
$=\frac{3\big(\frac{3\text{x}+2}{5\text{x}-3}\big)+2}{5\big(\frac{3\text{x}+2}{5\text{x}-3}\big)-3}$
After solving you will get
$f(f(x)) = x$
Also, $f^{-1}(x) = f(x)$ you can check.

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