# How do you solve -3x+y=-4 and 2x+y=1 using substitution?

Mar 4, 2016

The solution for the system of equations is:
color(green)(x=1
color(green)(y=-1

#### Explanation:

$- 3 x + y = - 4$.......equation $\left(1\right)$

$2 x + y = 1$

color(green)(y=1-2x..................equation $\left(2\right)$

Substituting equation $\left(2\right)$ in $\left(1\right)$:

$- 3 x + y = - 4$

$- 3 x + \textcolor{g r e e n}{1 - 2 x} = - 4$

$- 5 x + 1 = - 4$

$- 5 x = - 4 - 1$

$- 5 x = - 5$

$x = \frac{- 5}{- 5}$

color(green)(x=1

Finding $y$ from equation $2$:
$y = 1 - 2 x$

$y = 1 - 2 \times 1$

$y = 1 - 2$

color(green)(y=-1