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How do you solve the following system?: $2x -9y =-3 , -x +y = 8$

1 Answer

Nov 26, 2015

$x=-69/7$ ; $y=-13/7$

Explanation:

Given
[1] $color(white)("XXX")2x-9y=-3$
[2] $color(white)("XXX")-x+y=8$

[2] $xx 9 rarr$
$color(white)("XXX")$ [3] $color(white)("XXX")-9x+9y=72$

[1] $+$ [3] $rarr$
$color(white)("XXX")$ [4] $color(white)("XXX")-7x=69$

[4] $div (-7) rarr$
$color(white)("XXX")$ [5] $color(white)("XXX")x=-69/7$

[2] $xx 2 rarr$
$color(white)("XXX")$ [6] $color(white)("XXX")-2x+2y=16$

[1] $+$ [6] $rarr$
$color(white)("XXX")$ [7] $color(white)("XXX")-7y = 13$

[7] $div (-7) rarr$
$color(white)("XXX")$ [8] $color(white)("XXX")y=-13/7$

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