Question

find the inverse function in slope-intercept form ($mx+b$):
$f(x) = x + 9$

Explanation:

Step1: Replace $f(x)$ with $y$

$y = x + 9$

Step2: Swap $x$ and $y$

$x = y + 9$

Step3: Solve for $y$

$y = x - 9$

Step4: Replace $y$ with $f^{-1}(x)$

$f^{-1}(x) = x - 9$

Answer:

$f^{-1}(x) = x - 9$