计算：2/x+x²-1/x²-2x+1·x-1/x²+x；（1/a-3+1）÷a²-4/2a-6.

计算：2/x+x²-1/x²-2x+1·x-1/x²+x；（1/a-3+1）÷a²-4/2a-6.
计算：2/x+x²-1/x²-2x+1·x-1/x²+x；（1/a-3+1）÷a²-4/2a-6.

计算：2/x+x²-1/x²-2x+1·x-1/x²+x；（1/a-3+1）÷a²-4/2a-6.
因为（x的平方-2x+1）/（x的平方-1）÷（x-1）/（x的平方+x）-x的值与x无关：
（x的平方-2x+1）/（x的平方-1）÷（x-1）/（x的平方+x）-x
=(x-1)^2/[(x+1)(x-1)] * x(x+1)/(x-1) -x
=x -x
=0

(1)2/x+(x^-1)/(x^-2x+1)*(x-1)/(x^+x)
=2/x+(x+1)/(x-1)*(x-1)/[x(x+1)]
=2/x+1/x
=3/x.
(2)[1/(a-3)+1]÷(a^-4)/(2a-6)
=(a-2)/(a-3)×2(a-3)/[(a+2)(a-2)]
=2/(a+2).