SOLUTION: What is the number that best completes the sequence on: 2 9 5 13 10 19 17

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Question 898492: What is the number that best completes the sequence on: 2 9 5 13 10 19 17
Found 2 solutions by richwmiller, Edwin McCravy:
Answer by richwmiller(17219) (Show Source):
You can put this solution on YOUR website!
2 7 -11 23 -46 92 -184
9 -4 12 -23 46 -92 184
5 8 -11 23 -46 92
13 -3 12 -23 46
10 9 -11 23
19 -2 12
17 10
27

Answer by Edwin McCravy(20056) (Show Source):
You can put this solution on YOUR website!
2 9 5 13 10 19 17

The other tutor used a difference table. Here's a different approach which gives the same next term. Start with--------2 add 7, get 9 subtract 4, get 5 add 8, get 13 subtract 3, get 10 add 9, get 19 subtract 2, get 17 So it looks like the pattern is: 1. We alternate between adding and subtracting 2. The numbers we add go 7,8,9,etc 3. The numbers we subtract go 4,3,2,etc. The next thing to do is to add, and the next number to add is 10, so we have: Start-------------2 add 7, get 9 subtract 4, get 5 add 8, get 13 subtract 3, get 10 add 9, get 19 subtract 2, get 17 add 10, get 27 Edwin