解聯立方程

2x+y-1=0 …(1)
x-y+1=0 …(2)From(2),x-y+1=0x=y-1 …(3)sub(3)into(1)2(y-1)+y-1=02y-2+y-1=03y-3=03y=3y=1sub y=1 into(3)x=0