Question

решите систему уравнений


7x+y=-12,
у - х = 4.
Ответ:​

Answer 1

Смотри....................

Answer 2

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

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