How do you solve $xy=12$ and $5x-3y=-8$ ?

Question

1367 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-06-08T16:01:14

$y = 12/x$

$5x - 3(12/x) = -8$

$5x - 36/x = -8$

$(5x^2 - 36)/x = -8$

$5x^2 - 36 = -8x$

$5x^2 + 8x - 36 = 0$

$5x^2 - 10x + 18x - 36 = 0$

$5x(x - 2) + 18(x - 2) = 0$

$(5x + 18)(x - 2) = 0$

$x = -18/5 and 2$

$:. -18/5 xx y = 12 or 2 xx y = 12$

$y = 12/(-18/5) or y = 6$

$y = -10/3 or y = 6$

Our solution set is therefore ${-18/5, -10/3} and {2, 6}$ .

Hopefully this helps!

How do you solve xy=12xy=12 and 5x-3y=-85x-3y=-8?