Find the Law 15 10 13 9 11 8 () () 7 6

15 10 13 9 11 8 （9）（7） 7 6
This is a sequence of two!
The number of units is 15, 13, 11, 9, 7
The double digits are 10, 9, 8, 7, 6

RELATED INFORMATIONS

1. Find the rule 15,10,13,8,11, (), (), 4
2. Balmer formula was successfully obtained from spectral data 95161225213632 by Swiss middle school teacher, which opened the door of spectral mystery. Please write the seventh data according to this rule___ ．
3. Balmer, a Swiss middle school teacher, found the rule from spectral data 5 / 9, 12 / 16, 21 / 25, 32 / 36. Please write the seventh data ()
4. Balmer, a Swiss middle school teacher, found the rule from the spectral data 5 / 9, 12 / 16, 21 / 25, 32 / 36. Please write the number n according to the rule
5. Balmer, a Swiss middle school teacher, found the rule from the spectral data 5 / 9, 12 / 16, 21 / 25, 32 / 36. Please write the seventh number according to the rule
6. A set of data: 9 / 5, 16 / 12, 25 / 21, 36 / 32. What's the seventh number
7. Observe a group of fractions given, 9 out of 5, 16 out of 12, 25 out of 21, 36 out of 32,... Then the nth fraction can be expressed as
8. What's the law of this series of numbers?
9. Find the rules: 9 out of 5, 16 out of 12, 25 out of 21, 36 out of 32_____ ,...,____ (expressed by an algebraic expression containing n)
10. First find the rule, and then fill in the numbers 1, 4, 9, □, 25, 36, □, □
11. Find the rule: (3 / 1 / 4 / 1 = 3 / 4) (9 / 5 / 8 / 5 = 9 / 8) (11 / 7 / 15 / 7 = 11 / 15) (B / A / C / a =?)
12. Find the law 3 ^ 2 = 4 + 5, 5 ^ 2 = 12 + 13, 7 ^ 2 = 24 + 25, find the law, and prove the method
13. Fill in the blanks 0,1,3,8,21, () to explain the reason for the result
14. Fill in the blanks 2,4,8, () () 32,
15. 7,6,14,5,21,4,（）,（）,（）,（） 1,3,9,27,（）,（）,（） 1,3,7,15（）,63,（）,（） 1,4,9,（）,25,36,（）,（） 2 / 3, 3 / 8, 4 / 15, 5 / 24, (), (), () Complete the fifth line in the following table one thousand nine hundred and ninety-one 1991 1991 1991 3982 1991 1991 5973 5973 1991
16. Sky puzzle math problem The number of students in class 6 (1) ranges from 50 to 70. The ratio of boys to girls is 9:7. How many students are there in class 6 (1)?
17. Sky math Fill in the blanks 1. If you want to put a long and thin iron wire in a cube wooden box with 5 edges, the maximum length of the iron wire may be ()
18. Root a ^ 2 = () (a > 0) ()(a=0) ()(a
19. Mathematical calculation 123 As shown in the figure, M is a moving point on ad in the parallelogram ABCD to know that the area of the parallelogram ABCD is a, so does the area of the triangle MBC change? Why?
20. Mathematical puzzle 123 If C is a positive integer, and a + B = C, B + C = D, D + a = B, then what is the minimum value of (a + b) (B + C) (c + D) (D + a)?