(1+1/x)•x^2-2x+1/x^2-1

问题描述:

(1+1/x)•x^2-2x+1/x^2-1

=(x+1)/x ×(x-1)²/(x+1)(x-1)
=(x+1)/x× (x-1)/(x+1)
=(x-1)/x