|a+3b+1|+(2a+4)^2=0
2a+4=0
a=-2
a+3b+1=0
3b-1=0
b=1/3
3a^2b-[2ab^2-2(ab-3/2a^2b)]+2ab
=3a²b-2ab²+2ab-3a²b+2ab
=4ab-2ab²
=4×（-2）×1/3-2×（-2）×1/9
=-8/3+4/9
=-20/9