|2a+1|+(b-3)平方=0∴2a+1=0 b-3=0∴a=-1/2b=35(3a平方b-ab平方)-4(-ab平方+3a平方b)=15a²b-5ab²+4ab²-12a²b=3a²b-ab²当a=-1/2,b=3时原式=9/4+9/2=27/4