(3a^2b+1/帆慧4ab^2)-(3/态春答4ab^2+a^2b)=3a^2b-a^2b+1/4ab^2-3/4ab^2=2a^2b-1/森慎2ab^2=1/2ab(4a-b)
=1/2ab(4a-b)
