Question

Розвязати систему способом підстановки x-y=5 2x+y=7

Answer 1

Ответ:

4 ; -1

Объяснение:

$\left \{ {{x-y=5} \atop {2x+y=7}} \right.\\\\\left \{ {{x=5+y} \atop {2*(5+y)+y=7}} \right.\\\\\left \{ {{x=5+y} \atop {10+3y=7}} \right.\\\\\left \{ {{x=5+y} \atop {3y=-3}} \right.\\\\\left \{ {{x=5-1} \atop {y=-1}} \right.\\\\\left \{ {{x=4} \atop {y=-1}} \right.$