# How do you solve 5x+4y = -1 and 2x+y = -4?

Apr 22, 2018

$x = - 5$ and $y = 6$

#### Explanation:

Simultaneous linear equations:

$5 x + 4 y = - 1$
$2 x + y = - 4$

We want to cancel out either y or x so we only solve for one of them first.

Multiply the first equation by 2 and second equation by 5, so that the x's will cancel out:

$10 x + 8 y = - 2$
$10 x + 5 y = - 20$

Then subtract:

$3 y = 18$
$y = \frac{18}{3}$
$y = 6$

Substitute $y$ back into one of the original equations (I chose $5 x + 4 y = - 1$):

$5 x + 4 \left(6\right) = - 1$
$5 x + 24 = - 1$
$5 x = - 1 - 24$
$5 x = - 25$
$x = - \frac{25}{5}$
$x = - 5$

Hope this helped.