Question

розвязати систему
{5(x+y)+2(x-y)=120
{2(x+y)+(x-y)=51

Answer 1

x=120/7-3/7y
2(x+y)+(x-y)=51

2(120/7-3/7y+y)+(120/7-3/7y-y)=51

y=3/2

x=120/7-3/7•3/2

x=33/2

ответ: (x;y)=(33/2;3/2)