How do you solve by the substitution method to find the ordered pair 2x + 5y = -11 and x = -4 - 4y?

May 5, 2018

Refer to Explanation

Explanation:

$2 x + 5 y = - 11 \to$ Eqn 1
$x = - 4 - 4 y \to$ Eqn 2

Substitute Eqn 2 into Eqn 1:
$2 \left(- 4 - 4 y\right) + 5 y = - 11$
$- 8 - 8 y + 5 y = - 11$
$- 8 - 3 y = 11$
$- 3 y = - 19$
$y = 6 \frac{1}{3}$

Substitute $y = 6 \frac{1}{3}$ into Eqn 2:
$x = - 4 - 4 \left(6 \frac{1}{3}\right)$
$x = - 21 \frac{1}{3}$

$\therefore x = - 21 \frac{1}{3} , y = 6 \frac{1}{3}$