# How do you solve y = 2x + 9 and 2x - y = -9?

Nov 7, 2015

There are infinite possible solutions because the equations are the same.

#### Explanation:

You have the equations:
$1 : y = 2 x + 9$
$2 : 2 x - y = - 9$

Let's try to play around with the second one...
$2 x - y = - 9$
$- y = - 9 - 2 x$
$y = 2 x + 9$

You get the same equation as the first one!

If you plot those into the same coordinate system, you see that there are an infinite amount of possible solves.