x^2+2xy+y^2=25 (x+y)^2=25x+y=±5当x+y=5时x^2-y^2-x-y=6(x-y)(x+y)-(x+y)=6(x-y-1)(x+y)=65(x-y-1)=6x-y-1=6/5x-y=11/5x+y=5解得x=18/5y=7/5当x+y=-5时x^2-y^2-x-y=6(x-y)(x+y)-(x+y)=6(x-y-1)(x+y)=6-5(x-y-1)=6x...