Carefully observe the law of numbers, what is the most suitable to fill in the horizontal line 1, 8, 9, 4, 1 / 6 A.3 B.2 C.1 D.1 / 6 The second question is a sharp turn of the brain What is made on the same day as the expiration date

Carefully observe the law of numbers, what is the most suitable to fill in the horizontal line 1, 8, 9, 4, 1 / 6 A.3 B.2 C.1 D.1 / 6 The second question is a sharp turn of the brain What is made on the same day as the expiration date

A
daily

Mathematical rules, 1, 3, 5, 7, 9, 8, 12_ , 2, 20, 5, 9, 12, 8, 19 please fill in the numbers on the line
9 and 8 are spaces, 20 and 5 are also spaces!

14
Divide the number in the middle of each column by 2 plus the first = the third
1 3 5 7 9
8 12 14 2 20
5 9 12 8 19
1+8/2=5
3+12/2=9
5+14/2=12
7+2/2=8
9+20/2=19

Observe the following group of numbers. According to a certain rule, add appropriate numbers to the horizontal line, 1 / 3, - 2 / 15,3 / 35, - 6 / 63

1/3,-2/15,3/35,-6/63,12/99,-24/143,48/195,-96/255,…… The law is: one positive and one negative, which is obvious. The general term of denominator is the law of (2n-1) (2n + 1) molecule. The third term is equal to the sum of the first two terms, and the fourth term is equal to the sum of the first three terms The nth term is equal to the sum of the first n-1 terms