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

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Answer 1 · 2018-04-22T21:38:34

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

Simultaneous linear equations:

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

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:

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

Then subtract:

$3y = 18$
$y = 18/3$
$y=6$

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

$5x + 4(6) = -1$
$5x + 24 = -1$
$5x = -1-24$
$5x = -25$
$x = -25/5$
$x= -5$

Hope this helped.