How do solve the following linear system?: $x - 3y = 1, y = 4x + 4$ ?

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Answer 1 · 2017-12-09T19:58:06

$x=-13/11, y=-8/11$

Since one of the equations is given to us as $y=...$ , we can substitute this into the first equation.

Subst. eqn 2 into eqn 1

$x-3(4x+4)=1$
$x-12x-12=1$
$-11x=13$
$x=-13/11$

Subst. back into either of the other equations (I'll use the second, but both work).

$y=4(-13/11)+4$
$y=-8/11$

How do solve the following linear system?: x - 3y = 1, y = 4x + 4 x - 3y = 1, y = 4x + 4 ?