初二二元方程组方程题目一道

x²-2xy+y²=1则(x-y)²=1则x-y=1或x-y=-1
2x²-5xy-3y²=0则(2x+y)(x-3y)=0,则2x+y=0或x-3y=0
联立x-y=1,2x+y=0,解得x=1/3,y=-2/3
联立x-y=1,x-3y=0,解得x=3/2, y=1/2
联立x-y=-1,2x+y=0,解得x=-1/3,y=2/3
联立x-y=-1,x-3y=0,解得x=-3/2,y=-1/2
以上四组均是方程的解.