当a=负一,b= 负三,c=2分之1时,求2分之1a的平方b-[2分之3a的平方b-2(3abc-4a的平方b)]
问题描述：
当a=负一,b= 负三,c=2分之1时,求2分之1a的平方b-[2分之3a的平方b-2(3abc-4a的平方b)]
答
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