# What is the solution set for -9x + 3y = -9 and 3x +4y = -9?

Aug 22, 2015

The solutions are
color(blue)(x=1/5, y=-12/5

#### Explanation:

$- \textcolor{b l u e}{9 x} + 3 y = - 9$.....equation $1$

$3 x + 4 y = - 9$, multiplying by $3$
$\textcolor{b l u e}{9 x} + 12 y = - 27$.....equation $2$

Solving by elimination
Adding equations $1$ and $2$
$- \cancel{\textcolor{b l u e}{9 x}} + 3 y = - 9$
$\cancel{\textcolor{b l u e}{9 x}} + 12 y = - 27$

$15 y = - 36$
color(blue)(y=-12/5

Finding $x$ from equation $2$
$3 x + 4 y = - 9$

$3 x = - 9 - 4 y$

$x = \frac{- 9 - 4 y}{3}$

$x = \frac{3}{15}$

color(blue)(x=1/5