Решите пожалуйста......

Ответ:

1) { y = 2x + 5.

{2x + 3y = 31.

2x + 3(2x+5) = 31.

x = 2.

y = 2 × 2 + 5.

y = 9.

{ 9 = 2 × 2 + 5.

{ 2 × 2 +3 × 9 = 31.

{ 9 = 9.

{ 31 = 31.

(x, y) = (2, 9).

2) {5x - 7y = - 24.

{x = - 3y + 4.

5(-3y + 4) - 7y = - 24.

y = 2.

x = - 3 × 2 + 4.

x = - 2.

{ 5×(-2) - 7 × 2 = - 24.

{ -2 = - 3 × 2 + 4.

{ -24 = - 24.

{ - 2 = - 2.

(x, y) = ( - 2, 2).