题目内容：

计算(1+1/x)÷(2x-1+x²/x) 2x/x²-9+1/3-x+x+2/x+3
81ab²×(abc)^4÷(-9a²b^3c)÷[3(abc)^3]

优质解答

(1+1/x)÷(2x-1+x²/x) =（1+x）/x ÷(2x²-1-x²)/x=(1+x)÷（x²-1）=(1+x)÷(x+1)(x-1)=1/(x-1)2x/x²-9+1/3-x+x+2/x+3=2x/(x-3)(x+3) -1/(x-3) +(x+2)/(x+3)=[2x-(x+3)+(x+2)]/(x-3)(x+3)=[...