(2/1+a)-(a-2/a-1)÷(a²-2a/a²-2a+1)等于多少

【1】a+a=a×a a= [ ]【2】a×a=a÷a a=[ ]【3】a×a=a－a a=[ ] [4]a－a=a＋a a=[ ] (a 1)(a 2)(a 3)(a (a+2)(a+1)-a(a-3) (1-16a×a×a×a)÷（4a×a+1)÷(2a+1)² (1-16a×a×a×a)÷(4a×a+1)÷(2a+1) [(a/a-2)-(a/a+2)]÷4a/2-a,其中a=-1/2 [a-a/(a+1)]÷(a²-2a)/(a²-4)×(a+1)/(a²+4a+4) a-1/a+2 1-a/-2-a -2×a×1/a 先化简,再求值:(a-1/a-a-2/a+1)÷2a^2-a/a^+2a+1,其中a满足a^2-a-1=0 计算：[a-(1/a)]/a^2-2a+1/a a-1/a+2÷a²-2a+1/a²-4×a+3/a²+a-6 化简：[(a-2)/(a²+2a)-(a-1)/(a²+4a+4)]÷(a-4)/(a+2) 化简:｛(a+2/a²-2a)-(a-1/a²-4a+4)｝÷(a-4/a) a(a-1)(a-2)(a-3)(a-4)因式分解 a/a+2-1/a-1÷a+2/a²-2a+1 化简：(a/a-1-2a-1/a-1)÷a-1/a+2