Question

решите систему уравнений


7x+y=-12,
у - х = 4.
Ответ:​

Answer 1

Смотри....................

Answer 2

$displaystyle tt left { {{7x+y=-12} atop {y-x=4}} right. : to : left { {{7x+y=-12} atop {y=4+x}} right. \\\ displaystyle tt 7x+4+x=-12\displaystyle tt 8x=-12-4\displaystyle tt 8x=-16\displaystyle tt x=-16div8\displaystyle tt bold{x=2}\\ displaystyle tt y=4+(-2)\displaystyle tt y=4-2\displaystyle tt bold{y=2}$

ОТВЕТ: $displaystyle tt (x; : y)=(-2; : 2)$