How do you solve the following system?: $2x + 7y = -8, x - 2y = 7$

Question

1890 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-04-21T14:52:47

$x = 3$ and $y = -2$

$2x + 7y = -8 color(white)(....) ——(1)$
$x - 2y = 7 color(white)(....) ——(2)$

Multiply second equation by $2$
$2x - 4y = 14 color(white)(....) ——(3)$

Subtract $3$ nd equation from $1$ st

$2x + 7y - (2x - 4y) = -8 - 14$

$2x + 7y - 2x + 4y = -22$

$11y = -22$

$y = -22/11$

$y = -2$

Substitute $y = -2$ in equation $(1)$

$2x + (7 × -2) = -8$

$2x - 14 = -8$

$2x = 14 - 8$

$2x = 6$

$x = 6/2$

$x = 3$

How do you solve the following system?: 2x + 7y = -8, x - 2y = 7 2x + 7y = -8, x - 2y = 7