Question

Resolva o sistema {-x+4y=9 ALGEBRICAMENTE
                           {2x-4y=-6

Answer 1

-2x + 8y = 18
2x + 4y = -6

12 y = 12
y = 1

-2x + 8y = 18
-2x + 8 =18
- 2x = 10
x = -5

Answer 2

$\left \{ {{-x+4y=9} \atop {2x-4y=6}} \right. <=> \left \{ {{x=-9+4y} \atop {2(-9+4y)-4y=6}} \right. <=> \left \{ {{---} \atop {4y =24 }} \right. <=> \left \{ {{x=-9+4*6} \atop {y=6}} \right.$

x= 15
y = 6