Question

решите системы уравнений​

Answer 1

$3)3x - 5y = 23 \: \: | \times 2 \\ 2x + 3y = 9 \: \: | \times ( - 3) \\ \\ 6x - 10y = 46 \\ - 6x -9 y = - 27$

Складываем

$- 19y = 19 \\ y = 9 \div ( - 19) \\ y = - 1$

$2x + 3y = 9 \\ 2x + 3 \times ( - 1) = 9 \\ 2x - 3 = 9 \\ 2x = 9 + 3 \\ 2x = 12 \\ x = 12 \div 2 \\ x = 6$

Ответ : (6 ; -1)

$4)6x + 5y = 0 \\ 2x + 3y = - 8 \: \: | \times ( - 3) \\ \\ 6x + 5y = 0 \\ - 6x - 9y = 24$

Складываем

$- 4y = 24 \\ y = 24 \div ( - 4) \\y = - 6$

$2x + 3y = - 8 \\ 2x + 3 \times - 6 = - 8 \\ 2x - 18 = - 8 \\ 2x = - 8 + 18 \\ 2x = 10 \\ x = 10 \div 2 \\ x = 5$

Ответ: (5 ; -6)