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

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Answer 1 · 2016-02-07T17:44:56

$y = \frac{x - 9}{3}$ $y=(x-9)/3$

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

$y = 3 x + 9$ $y = 3x + 9$

$y - 9 = 3 x$ $y - 9 = 3x$

$\frac{y - 9}{3} = x$ $(y-9)/3 = x$

$x = \frac{y - 9}{3}$ $x = (y-9)/3$

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

$y = \frac{x - 9}{3}$ $y = (x-9)/3$

Here's a graph of both functions together:

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