Cateva ex va roggggg

Răspuns:
a. x=10-y
2×10-y=8 =>
20-y=8 => -y=8-20 =>
-y=-12 /×(-1) => y=12 =>
x=10-12 => x=-2
S={(-2, 12)}
b. x=1-y
1-y+2y=-1 =>
1-y=-1 => y=-1-1 => y=-2 =>
x=1-2 => x=-1
S={(-1, -2)}