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

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Answer 1 · 2016-06-25T18:08:39

$x = 3$ $x = 3$ and $y = - 7$ $y = -7$

We already know that $y = - 3 x + 2$ $y = -3x + 2$
So we must substitute $y$ $y$ (in the equation) for $- 3 x + 2$ $-3x + 2$
So...

$- 3 x + 2 + x = - 4$ $-3x + 2 + x = -4$
$- 2 x + 2 = - 4$ $-2x + 2 = -4$
$- 2 x = - 6$ $-2x = -6$
$2 x = 6$ $2x = 6$
$x = 3$ $x = 3$

So...

$3 + y = - 4$ $3 + y = -4$
$y = - 7$ $y =-7$

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