已知a=1-根号2,先化简,再求(a²-1)/(a²+a)+根号（ a²-2a+1)/(a²-a)值

（a²-1）/（a²+a）+根（a²-2a+1）/（a²-a）=(a+1)(a-1)/a(a+1）+根（a-1）²/a（a-1)=(a-1)/a+|a-1|/a(a-1). 因为a=1-根2＜0,所以|a-1|=-（1-a）原式=（a-1）/a-1/a=（a-2）/a=（根2+1）/（根2-1）=3+2根2..