a-2的绝对值+(b+1)²=0
绝对值和平方都大于等于0
所以a-2=0,b+1=0
a=2,b=-1
9a²-4ab+3b²-(5a²-3ab+2分之3b²)
=9a^2-4ab+3b^2-5a^2+3ab-3/2b^2
=4a^2+3/2b^2-ab
=16+3/2+2
=18+3/2
=39/2