How do you solve $x y = 144$ $xy=144$ and $x - y = 18$ $x-y=18$ ?

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Answer 1 · 2016-04-22T09:12:38

Use substitution and factoring

$x y = 144$ $xy=144$
$x - y = 18$ $x-y = 18$
$:.x = 18+y$

Substituting this into the first equation gives
$(18+y)y=144$
$18y +y^2 - 144=0$
$(y^2+18y-144)=0$
$(y+24)(y-6)=0$

$y=-24$ or $y=6$
$x=-6$ or $x=24$

How do you solve xy=144xy=144xy=144 and x-y=18x−y=18x-y=18?