Question

5x - 4y = 12
2x - 4y = 6

Answer 1

5x - 4y = 12

5x = 12 + 4y

5x = 12/4y

5x = 3

x = 3 - 5

x = -2

_______________

2x - 4y = 6

2 • (-2) - 4y = 6

-4 - 4y = 6

-4y = 6 + 4

-4y = 10

y = 10 + 4

y = 14

Answer 2

Resposta:

Método da adição

$5x-4y=12~.~(-1)\\ \\ \\~~~~~~ -5x+4y=-12~equacao~I\\ +~~~~~~2x-4y=~~~~6 ~equacao~II\\ ~~~~--------\\ ~~~~~~-3x+~~0=~-6\\ \\ -3x=-6\\ \\ x=\frac{-6}{-3} \\ \\ x=2$

Substitua (x = 2) em uma das equações

$5x-4y=12\\ \\ 5.2-4y=12\\ \\ 10-4y=12\\ \\ -4y=12-10\\ \\ -4y=2~.(-1)\\ \\ 4y=-2\\ \\ y=-\frac{2}{4} =-\frac{1}{2} \\ \\ \\ S~~\left \{ {{2;~-\frac{1}{2} } {}} \}$