(x^2-1/x)/(x+1+1/x)= (x^3-1)/(x^2+x+1) 【分式的分子和分母同乘以x】= x-1x^3/(x-1)-x^2-x-1= x^3/(x-1)-(x^2+x+1)= [x^3-(x-1)(x^2+x+1)]/(x-1) 【通分】= [x^3-(x^3-1)]/(x-1)= 1/(x-1)