1-(x-1/1-x)^2÷x^2-x+1/x^2-2x+1,其中x^2-x+5=0=1-(x-x²-1)²/(1-x)²÷(x²-x+1)/(x-1)²=1-(x²-x+1)²/(x²-x+1)=1-x²+x-1=-(x²-x)=-(-5)=5
