How do you solve $3x -y = 4$ and $x + 2y = 13$ ?

Question

3815 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2015-12-21T16:12:42

The solution for the system of equations is
$color(blue)(x=3, y=5$

$3x-y=4$ , multiplying by $2$
$6x-color(blue)(2y)=8$ .....equation $1$

$x +color(blue)(2y)=13$ ....equation $2$

Solving by elimination

Adding equations $1$ and $2$

$6x-cancelcolor(blue)(2y)=8$

$x +cancelcolor(blue)(2y)=13$

$7x=21$

$x=21/7$

$color(blue)(x=3$

Finding $y$ from equation $1$

$3x-y=4$

$3x-4=y$

$3 xx color(blue)(3)-4=y$

$9 -4=y$

$color(blue)(y=5$

How do you solve 3x -y = 43x -y = 4 and x + 2y = 13x + 2y = 13?