Решите систему уравнений методом алгебраического сложения: 6y-5x=70 - 5x-6y=-50 4x+9y=20 4x-9y=-52 6x-7y=-14 6x+7y=98

1). {6 y - 5 x = 70;

{ - 5 x - 6 y = - 50;

(6 y - 5 x) - ( - 5 x - 6 y) = 70 - ( - 50);

12 y = 120; y = 10;

6 * 10 - 5 x = 70;

5 x = 60 - 70; x = - 2;

{x = - 2; y = 10;

2). {4 x + 9 y = 20;

{4 x - 9 y = - 52;

(4 x + 9 y) + (4 x - 9 y) = 20 - 52;

8 x = - 32; x = - 4;

4 * ( - 4) + 9 y = 20; - 16 + 9 y = 20;

9 y = 36; y = 4;

{x = - 4; y = 4;

3). {6 x - 7 y = - 14;

{6 x + 7 y = 98;

(6 x - 7 y) - (6 x + 7 y) = - 14 - 98;

- 14 y = - 112; y = 8;

6 x - 7 * 8 = - 14;

6 x = 42; x = 7;

{x = 7; y = 8;