答：
x1,x2是方程3x²-7根号3x+1=0的两个根
根据韦达定理：
x1+x2=7√3/3
x1*x2=1/3
x1³x2+x1x2³
=(x1²+x2²)(x1*x2)
=[(x1+x2)²-2x1*x2]*(1/3)
=(1/3)*[(7√3/3)²-2/3]
=(1/3)*(49/3-2/3)
=47/9