1:(-2)^n
2:3
3:x=5或-5
4:cd=1,a+b=0 题没写对
5:cd=1,a+b=0 5或-7
6:A-B=A+B-2B=7x²-8x+11
7:(1)128X0.5=64
(2)0.8a
(3)(147.8-150X0.5)÷0.8=91
8:(1)8.5-1.5=7
(2)8.5X2=17
9:a
1:(-2)^n
2:3
3:x=5或-5
4:cd=1,a+b=0 题没写对
5:cd=1,a+b=0 5或-7
6:A-B=A+B-2B=7x²-8x+11
7:(1)128X0.5=64
(2)0.8a
(3)(147.8-150X0.5)÷0.8=91
8:(1)8.5-1.5=7
(2)8.5X2=17
9:a