Solve for y in $2x + y = 1$ and $x - 2y =-7$ ?

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Answer 1 · 2015-04-07T17:15:07

If $2x+y=1$
then
$4x+2y = 2$

We can add the second equation to this to eliminate the $y$ term

$((,4x,+,2y,=,2),(+,x,-,2y,=,-7),(,5x,,,=,-5))$

$rarr x=-1$

Substituting $x=-1$ back into the original first equation we get
$2(-1) + y = 1$
which simplifies as
$y=3$

Solve for y in 2x + y = 12x + y = 1 and x - 2y =-7x - 2y =-7?