x²-3xy+2y²=0（x-y)(x-2y)=0x=yx=2y代入：y²+3y²=4y²=1y=±1x=±1即X=1,y=1x=-1,y=-1(2)(2y)²+3y²=4y²=4/7y=±2√7/7x=±4√7/7即X=4√7/7,y=2√7/7X=-4√7/7,y=-2√7/7...