{8x -10y = 428
{12x + 6y = 444
{ 2(4x -5y) = 2*214 |:2
{ 6(2x + y) = 6*74 |:6
{4x -5y = 214
{2x + y = 74 ⇒ y= 74 - 2x
Метод подстановки :
4х - 5(74 - 2х) = 214
4х - 5*74 - 5* (-2х) = 214
4х - 370 +10х = 214
14х = 214 + 370
14х =584
х= 584 : 14 = ²⁹²/₇
х = 41 ⁵/₇
у=74 - 2 * 41 ⁵/₇ = 74 - ⁵⁸⁴/₇ = 74 - 83 ³/₇ = - (83 ³/₇ - 74)
у= - 9 ³/₇
Ответ: ( 41 ⁵/₇ ; - 9 ³/₇ )