先化简,再求值:a-1分之a+2a+1-a-1分之a,其中a=根号3+1

问题描述:

先化简,再求值:a-1分之a+2a+1-a-1分之a,其中a=根号3+1

(a+2a+1)/( a-1)-a/(a-1)=(a+1)^2/(a+1)(a-1)-a/(a-1)=(a+1)/(a-1) -a/(a-1) =1/(a-1) 由a=根号3+1,所以原式=1/(a-1)=1/根号3=根号3/3.