a=根号2+1
[(a^2-1)/(a^2-2a+1)] + [(2a-a^2)/(a-2)] / a
= [(a+1)(a-1)/(a-1)^2] + [2(2-a)/(a-2)] / a
= [(a+1)/(a-1)] + [-2)] / a
= (a+1)/(a-1) - 2 / a
= (根号2+1+1)/(根号2+1-1) - 2 / (根号2+1)
= (根号2+2)/根号2 - 2(根号2-1) / (2-1)
= (1+根号2) - 2根号2 +2
= 3 - 根号2
追问如果不代入a,式子是怎样的
追答我试过了,通过那一步代入a是最简单的,如果不代入a继续通分反而繁琐。
什么事都要讲究效率是吧!
追问题目说先化简