a+1/a-1 - a/a^2-2a+1 ÷1/a,其中a=1-根号2 先化简再求值

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a+1/a-1 - a/a^2-2a+1 ÷1/a,其中a=1-根号2 先化简再求值

a+1/a-1 - a/a^2-2a+1 ÷1/a,其中a=1-根号2 先化简再求值
a+1/a-1 - a/a^2-2a+1 ÷1/a,其中a=1-根号2 先化简再求值

a+1/a-1 - a/a^2-2a+1 ÷1/a,其中a=1-根号2 先化简再求值
原式=(a+1)(a-1)/(a-1)²-a/(a-1)²×a
=(a²-1-a²)/(a-1)²
=-1/(a-1)²
=-1/(1-√2-1)²
=-√2/2

(a+1)/(a-1) - a/(a²-2a+1) ÷1/a
=(a+1)/(a-1) - a/(a-1)²×a
=(a+1)/(a-1) - a²/(a-1)²
=[(a+1)(a-1)-a²]/(a-1)²
=(a²-1-a²)/(a-1)²
=-1/(a-1)²
=-1/(1-√2-1)²
=-1/2