Вправи: 1095

1095. Знайди розв’язок системи рівнянь.

a) 3x + 1 = 5(3 – 2y);

4(x – 1) = 2(8,5 – 5y);

3x + 1 = 15 – 10y;

4x – 4 = 17 – 10y;

3x + 10y = 15 – 1;

4x + 10y = 17 + 4;

3x + 10y = 14;

4x + 10y = 21;

10y = 14 – 3x;

4x + 14 – 3x = 21;

x = 21 – 14;

x = 7;

10y = 14 – 3 • 7 = 14 – 21 = –7; y = –0,7.

Відповідь: (7; –0,7).

б) 6(x – 2y) = 7 – 9y;

8x + 3y = 5(2x + 1);

6x – 12y = 7 – 9y;

8x + 3y = 10x + 5;

6x – 12y + 9y = 7;

8x + 3y – 10x = 5;

6x – 3y = 7;

–2x + 3y = 5;

3y = 6x – 7;

–2x + 6x – 7 = 5;

4x = 5 + 7;

4x = 12;

x = 3;

3y = 6 • 3 – 7 = 11; y = 113 = 323.

Відповідь: (3; 323).