Question

已知x的平方减3x加1等于0，求x的立方加x立方分之一的值

我初三刚毕业。求多种不同解法。
木有.

Answer 1

初三了解出来就好了...真是...

x^2-3x+1=0

x-3+1/x=0 (obviously, x does not =0)

x+1/x=3

x^3+3x+3/x+1/x^3=27

x^3+1/x^3 = 27 - 3(x+1/x) = 27-3*3=18

Answer 2

x^2-3x+1=0

两边除以x

x+1/x=3

两边平方

x^2+1/x^2=9-2=7

x^3+1/x^3=(x+1/x)(x^2+1/x^2-1)=3(7-1)=18