x-1/x=3, (x-1/x)^2=9, x^2+1/x^2=7.x^3+1/x^3=(x+1/x)(x^2-1+1/x^2)=3*(7-1)=18.
题目是x²-3x-1=0 求x³+1/x³吗
这种书写让人很蛋疼，看不懂
