化简并带入求值 1/2（-3ax²-ax+3)-(-ax²-1/2ax-1) (其中a=-2 x=3)

题目

化简并带入求值 1/2（-3ax²-ax+3)-(-ax²-1/2ax-1) (其中a=-2 x=3)

答案

1/2（-3ax²-ax+3)-(-ax²-1/2ax-1)
=-3/2ax²-1/2ax+3/2+ax²+1/2ax+1
=-1/2ax²+5/2
代入得 -1/2*（-2）*3²+5/2
=9+5/2
=23/2