Question

Найдите решение системы уравнений {
х + у = 2,
х − у = −6

Answer 1

$left { {{x+y=2} atop {x-y=-6}} right. \left { {{x+y=2} atop {x=-6+y}} right. \-6+y+y=2\2y=8\y=4\x=-6+4=-2$

(-2;4)

Answer 2

$left{begin{array}{ccc}x+y=2\x-y=-6end{array}right;;;; Longrightarrow ;;;; left{begin{array}{ccc}x=2-y\-y+(2-y)=-6end{array}right \\\ -y+(2-y)=-6 \ 2 - 2y = -6 \ -2y = -6 - 2 \ -2y = -8 \\ y = dfrac{-8}{-2} \\ y = 4 \\\ x = 2 - 4 \ x = -2$

Ответ: (-2; 4)