# How do you solve 4x-y=-9 and 2x+y=-3?

Jun 15, 2016

$\left(x , y\right) = \left(- 2 , 1\right)$

#### Explanation:

[1]$\textcolor{w h i t e}{\text{XXX}} 4 x - y = - 9$
[2]$\textcolor{w h i t e}{\text{XXX}} \underline{2 x + y = - 3}$
[3]$\textcolor{w h i t e}{\text{XXX")6xcolor(white)("XxX")=-12color(white)("XXX}}$ after adding [1] and [2]

[4]$\textcolor{w h i t e}{\text{XXX")x=-2color(white)("XXXXXXX}}$after dividing both sides of [3] by $6$

[5]$\textcolor{w h i t e}{\text{XXX")-8-y=-9color(white)("XXXX}}$after substituting $\left(- 2\right)$ for $x$ in [1]

[6]$\textcolor{w h i t e}{\text{XXX")y=1color(white)("XXXXXXX}}$after adding $8$ to both sides of [5] then dividing by $\left(- 1\right)$