当a=负一,b=负三,c=2分之1时,

　　a²b/2-[3a²b/2-2(3abc-4a²b)]

　　=a²b/2-{3a²b/2-2[3×(-1)×(-3)×(1/2)-4×(-1)²(-3)]}

　　=a²b/2-[3a²b/2-(9-24)]

　　=a²b/2-3a²b/2+15

　　=-a²b+15

　　=-(-1)²(-3)+15

　　=12

　　那个。。。化简怎么化啊

　　当a=负一,b=负三,c=2分之1时，a²b/2-[3a²b/2-2(3abc-4a²b)]=a²b/2-3a²b/2-6abc+8a²b)=7a²b-6abc=7×(-1)²(-3)-6×(-1)×(-3)×(1/2)=21-9=12