解∵x1,x2是方程的根∴由韦达定理得：x1+x2=3x1x2=-1∴2x1+2x2=2(x1+x2)=2×3=61/x1+1/x2=(x2+x1)/(x1x2)=3/(-1)=-3/x1-x2/=√(x1-x2)²=√(x1+x2)²-4x1x2=√3²-4×(-1)=√9+4=√13x1²+x2²=...