# What is the inverse of y = 3x + 9?

Feb 7, 2016

$y = \frac{x - 9}{3}$

#### Explanation:

To find the inverse of a function, all we need to do is solve for the independent variable and then switch these variables.

$y = 3 x + 9$

$y - 9 = 3 x$

$\frac{y - 9}{3} = x$

$x = \frac{y - 9}{3}$

Switch $x$ for $y$ and vice versa:

$y = \frac{x - 9}{3}$

Here's a graph of both functions together: