Вправи: 1152

1152. Розв’яжіть систему рівнянь:

1) 6x + 3 = 5x – 4(5y + 4), 6x + 3 = 5x – 20y – 16,

3(2x – 3y) – 6x = 8 – y; 6x – 9y – 6x = 8 – y;

6x – 5x + 20y = –16 –3, x + 20y = –19, x + 20∙(–1) = –19, x = 1,

6x – 9y – 6x + y = 8; –8y = 8; y = –1; y =–1

Відповідь: (1; –1);

2) x+32 – y-47 = 1│∙14, 7(x + 3)–2(y – 4) = 14, 7x+21– 2y + 8=14,

6y – x = 5; 6y – x = 5; –x + 6y = 5;

7x – 2y = –15, 7(6y – 5) – 2y = –15, 42y – 35 – 2y = –15,

x = 6y – 5; x = 6y – 5; x = 6y – 5;

40y = 20, y = 0,5,

x = 6y – 5; x = –2.

Відповідь: (–2; 0,5);

3) x + y8 + x - y6 = 4│∙24, 3(x + y) + 4(x – y) = 96

3x + y4 – 2x - 5y3 = 5│∙ 12 3(3x + y) – 4(2x – 5y) = 60;

3x + 3y + 4x – 4y = 96, 7x – y = 96, 7(–23y + 60) – y = 96,

9x + 3y – 8x + 20y = 60; x + 23y = 60; x = –23y + 60;

–161y + 4250 – y = 96, –162y = –324, y = 2, y = 2,

x = –23y + 60; x = –23y + 60; x = –23 ∙2+60; x = 14.

Відповідь: (14; 2).