Відповіді на вправи: 519 (1-2)

1) x + y = 8;

xy = 7;

x = 1; x = 7;

y = 7; y = 1.

Відповідь: (1; 7), (7; 1).

2) x² + y² = 14;

xy = 6 |• 2;

+ x² + y² = 13;

2xy = 12;

x² + 2xy + y² = 25;

(x + y)² = 25;

x + y = –5; x + y = 5;

xy = 6; xy = 6;

x = –2; x = –3; x = 2; x = 3.

y = –3 y = –2; y = 3; y = 2.

3) 9x² + y² = 34;

xy = 5 |• 6;

+ 9x² + y² = 34;

6xy = 30;

9x² + 6xy + y² = 64;

(3x + y)² = 64;

3x + y = –8; 3x + y = 8;

xy = 5; xy = 5;

4) + x + y – xy = 1;

x + y + xy = 5;

2x + 2y = 6|: 2;

x + y = 3;

x + y = 3;

3 + xy = 5;

x + y = 3;

xy = 2;