Question

решите систему уравнений

Answer 1

$7x + 6y = 6 \: \: | \times 2\\ 3x + 4y = 9 \: \: | \times ( - 3)\\ \\ 14x + 12y = 12 \\ - 9x - 12y = - 27$

Складываем

$5x = - 15 \\ x = - 15 \div 5 \\ x = - 3 \\ \\ 3x + 4y = 9 \\ 4y = 9 - 3x \\ 4y = 9 - 3 \times ( - 3) \\ 4y = 9 + 9 \\ 4y = 18 \\ y = \frac{18}{4} \\ y = \frac{9}{2} \\ y = 4.5$

Ответ: (-3 ; 4.5)