先化简,再求值:(a²b-2ab²-b³)÷b-(a+b)(a-b),其中a=-1,b=1/2.
问题描述:
先化简,再求值:(a²b-2ab²-b³)÷b-(a+b)(a-b),其中a=-1,b=1/2.
答
(a²b-2ab²-b³)÷b-(a+b)(a-b)
=a²-2ab-b²-(a²-b²)
=a²-2ab-b²-a²+b²
=-2ab
=-2*(-1)*(1/2)
=1