原式=a-a+2/3b²-3/2a+1/3b²
=b²-3/2a
∵ (a-3)²+│b+2│=0
∴(a-3)²=0且│b+2│=0即a-3=0,b+2=0
∴a=3,b=-2
代入上式得：3²-3/2×（-2）=12