Question

if
$f(x) = \frac{1}{9} x - 2$
what is
${f}^{ - 1} (x)$
​

Answer 1

Let $y = f^{-1}(x)$ and $f(y) = x$

$\frac{1}{9}y - 2 = x\\\frac{1}{9}y = x + 2\\y = 9x + 18\\f^{-1}(x) = 9x + 18$