How do you solve the system $x - 3y = -3$ , $x + 3y = 9$ ?

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Answer 1 · 2015-11-21T00:03:33

$(3,2)$

We can use linear combination.

Add the two equations together (notice that the $y$ terms will cancel out):

$x-3y=-3$
$x+3y=9$
$2x=6$

Therefore, if we divide both sides by $2$ , we see that $x=3$ . We can then plug $3$ back into either equation for $x$ in order to solve for $y$ .

(Plugging into the first equation:)
$3-3y=-3$
$-3y=-6$
$y=2$

Since $x=3$ and $y=2$ , we can write our answers in an ordered pair: $(3,2)$ .

How do you solve the system x - 3y = -3x - 3y = -3, x + 3y = 9x + 3y = 9?