Question

Помогите срочно!!!!! 1){2х-3у+1+(х-у+5)=0 {5х+7у-(8х+у+1)=0

Answer 1

$2x - 3y + 1 + (x - y + 5) = 0 \\ 5x + 7y - (8x + y + 1) = 0 \\ \\ 2x - 3y + 1 + x - y + 5 = 0 \\ 5x + 7y - 8x - y - 1 = 0 \\ \\ 3x - 4y + 6 = 0 \\ - 3x + 6y - 1 = 0$

Складываем

$2y + 5 = 0 \\ 2y = - 5 \\ y = - 5 \div 2 \\ y = - 2.5 \\ \\ 3x - 4y + 6 = 0 \\ 3x - 4 \times ( - 2.5) + 6 = 0 \\ 3x + 10 + 6 = 0 \\ 3x + 16 = 0 \\ 3x = - 16 \\ x = - 16 \div 3 \\ x = - 5 \frac{1}{3} \\ \\ otvet \: ( - 5 \frac{1}{3} \: ; \: - 2.5)$