How do you solve the following linear system $-4x +9y = 5 , x - 4y = -3$ ?

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Answer 1 · 2016-06-15T11:50:38

$x=1; y=1$

First, let's obtain x in the second equation:
$x=4y-3$

then let's substitute its value in the first one:
$-4(4y-3)+9y=5$

then, by simplifying:
$-16y+12+9y=5$
$-16y+9y=-12+5$
$-7y=-7$
$y=1$

and now let's substitute the value of y in
$x=4y-3$

so that
$x=4*1-3$
$x=1$

How do you solve the following linear system -4x +9y = 5 , x - 4y = -3 -4x +9y = 5 , x - 4y = -3 ?