Question

помогите пожалуйста ​

Answer 1

Ответ:

$x + y = 5 \\ + \\ x - y = 7 \\ \\ 2x = 12 \\ x = 6 \\ y = x - 7 = 6 - 7 = - 1$

(6; -1)

$3x - 5y = 20 \\ - \\ x + y = 4 \: | \times 3 \\ \\ 3x - 5y + 5x + 5y = 20 + 20 \\ 8x = 40 \\ x = 5 \\ y = 4 - x = 4 - 5 = - 1$

(5; -1)

$3x - 2y = 2 \\ - \\ x + 3y = - 3 | \times 3 \\ \\ 3x - 3x - 2y - 9y = 2 + 9 \\ - 11y = 11 \\ y = - 1 \\ x = - 3 - 3y = - 3 + 3 = 0$

(0; -1)