∵a,b是方程的x的平方-3x-2=0两个根
∴a²-3a-2=0 a+b=3 ab=-2
∴a³-3a²-2a=0
∴a³=3a²+2a
∴a³+3b²+2b=3a²+2a+3b²+2b=3(a+b)²-6ab+2(a+b)=3×3²-6×(-2)+2×3=27+12+6=45