2x-2y+1=0 2y=2x+1
2x=2y-1
x=y-1/2 y=x+1/2
分别代入方程：3x-2y+1=0得
3(y-1/2)-2(x+1/2)+1=0
3y-3/2-2x-1+1=0
2x-3y+3/2=0
4x-6y+3=0