你好, 小海星美美： x²y-xy²-x+y=x²y-xy²-(x-y)=xy(x-y)-(x-y)=(xy-1)(x-y)=56又∵xy=8∴(8-1)(x-y)=56,7(x-y)=56x-y=56/7=8∴x²+y²=x²+y²-2xy+2xy=(x-y)²+2x...