How do you solve 2x+9y=17, x=7-4y?

Feb 25, 2017

x= -5
y= 3

Explanation:

Generally, you can solve linear systems in different ways:

1) Graphing

2) Substitution

3) Elimination.

In this case, since x is already isolated in the second equation, we would use substitution.

$2 x + 9 y = 17$ Then we substitute $x = 7 - 4 y$

$2 \left(7 - 4 y\right) + 9 y = 17$

$14 - 8 y + 9 y = 17$

$y = 3$

Then solve for x using either equation (I picked the second one)

$x = 7 - 4 y$
$x = 7 - 4 \left(3\right)$
$x = - 5$