Системы уравнений: 1) { (x+y) y=12 { x-3y=-8 2) { 2x+y^2=5 { 4x+3y=5

1)

{ (x + y) y = 12;

{x - 3y = - 8; { (3y - 8 + y) y = 12;

{x = 3y - 8; { (4y - 8) y = 12;

{x = 3y - 8; { (y - 2) y = 3;

{x = 3y - 8; {y^2 - 2y - 3 = 0;

{x = 3y - 8; D/4 = 1 + 3 = 2^2; y = 1 ± 2; [{y = - 1;

[{x = 3 * (-1) - 8;

[{y = 3;

[{x = 3 * 3 - 8; [{y = - 1;

[{x = - 11;

[{y = 3;

[{x = 1.

2)

{2x + y^2 = 5;

{4x + 3y = 5; {4x + 2y^2 = 10;

{4x = 5 - 3y; {5 - 3y + 2y^2 - 10 = 0;

{4x = 5 - 3y; {2y^2 - 3y - 5 = 0;

{x = 5/4 - 3y/4; D = 3^2 + 4 * 2 * 5 = 49 = 7^2; y = (3 ± 7) / 4; y1 = (3 - 7) / 4 = - 1; y2 = (3 + 7) / 4 = 5/2; [{y = - 1;

[{x = 5/4 + 3/4;

[{y = 5/2;

[{x = 5/4 - 3/4 * 5/2; [{y = - 1;

[{x = 2;

[{y = 5/2;

[{x = - 5/8.

Ответ:

1) (-11; - 1), (1; 3); 2) (2; - 1), (-5/8; 5/2).