How do you solve the following linear system: $x + y = -3, y = 2x$ ?

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Answer 1 · 2018-03-28T17:43:49

$x=-1$
$y=-2$

Solve by substitution:
$x+y=-3$
$y=2x$

Since you were already given that $y=2x$ plug it into the first equation to solve for x:

$x+ (2x) = -3$ (Combine like terms)
$3x=-3$ (Divide by 3 to isolate variable)
$x=-1$

Now that you have solved for x, plug it into either equation to solve for y:

$y=2(-1)$
$y=-2$

Check the answer by plugging in both variables into equation 1:

$-1+ (-2)=-3$
$-3=-3$

How do you solve the following linear system: x + y = -3, y = 2x x + y = -3, y = 2x ?