x²-2xy+y²分之x²-y²,其中x²+y²-2x-6y+10=0 先化简,再求值
问题描述：
x²-2xy+y²分之x²-y²,其中x²+y²-2x-6y+10=0 先化简,再求值
答
x²+y²-2x-6y+10=0x²-2x+1+y²-6y+9=0(x-1)²+(y-3)²=0(x-1)²=0,(y-3)²=0x=1y=3(x²-y²)/(x²-2xy+y²)=(x-y)(x+y)/(x-y)²=(x+y)/(x-y)=(1+3)/(1-3)=-2