1,-2i
2, greater than or equal to-1
3, 1/2
4, 1
5,( 1,2]
6, 32 or 64 Parties
7, 2/5
8, 4/7
9,8 or 1 or 1/8
10,x-4y+3=0
1 1,3/4
12,2 root number 2
C A B D
17, (1) The root number of the reduction to absurdity (2)2/3
18, when A 2 and B 5, the maximum is 20.
19,( 1) 4 (2)
20, (1) y 2 = 4x (2) divided by (4,0)
2 1, (1) equidistant p=2 q= 1 equidistant p=-r q=0.
(2), (3) I don't have the answer here, but the way of (2) is that after the formula is listed, both sides are divided by 2 n to form a arithmetic progression.