∵a²+3a+1=0,b²+3b+1=0
∴a,b是方程x²+3x+1=0的解
∴a+b=-3,ab=1
a²b+ab²
=ab(a+b)
=1×(-3)
=-3
1/a+1/b
=(a+b)/ab
=-3/1
=-3