How do you solve the system $2x + y = 5$ and $x - 2y = -5$ ?

Question

4403 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-05-22T15:02:57

You can isolate one variable in one equation and then substitute its value in the other, as follows.

Let's, for example, isolate $y$ in the first one.

$y=5-2x$

Now, substitute it in the second:

$x-2(5-2x)=-5$
$x-10+4x=-5$
$5x=5$
$x=1$

Substituting this value in the $y=5-2x$ ,

$y=5-2(1)$
$y=3$

How do you solve the system 2x + y = 52x + y = 5 and x - 2y = -5x - 2y = -5?