先化简,再求值:(x-2)/(x^2-1)÷(2x+2)/(x^2+2x+1)+1/(x-1),其中x=根号2+1

问题描述:

先化简,再求值:(x-2)/(x^2-1)÷(2x+2)/(x^2+2x+1)+1/(x-1),其中x=根号2+1

(x-2)/(x^2-1)÷(2x+2)/(x^2+2x+1)+1/(x-1)=(x-2)/(x-1)(x+1)÷2(x+1)/(x+1)²+1/(x-1)=(x-2)/(x-1)(x+1)*(x+1)/2+1/(x-1)=(x-2)/2(x-1)+1/(x-1)=[(x-2)+2]/2(x-1)=x/2(x-1)=(√2+1)/2(√2+1-1)=(2+√2)/4