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avatar+-19 

The sequence beginning with 3, 7... follows this rule:

 Apr 14, 2019
 #1
avatar+644 
+1

So since 7 is the second term, we multiply 2 by 4 and add it to 7. We get 15

 

Our sequence so far: 3,7,15,

 

Then we multiply 4 and 4 to get 16 as 15 is the FOURTH term then add 16 to 15. We get 31.

 

Do you notice a pattern? 3,7,15,31.

 

Yes 2n+1 can represent each change for the terms.

 

So we keep calculating...

 Apr 14, 2019
edited by Guest  Apr 14, 2019
edited by CalculatorUser  Apr 14, 2019
 #2
avatar+101739 
+2

A little confusing, but....

 

Term  number   1   2    3     4     5      6     7

                          3  7   15    27   43   63   87

 

Note that the 3rd term  = previous term + 4 times the previous term number  = 7 + 4(2) = 15

 

4th term  =  15 + 4(3)  = 27

5th term = 27 + 4(4)  = 43

6th term =  43 + 4(5) = 63

7th term = 63 + 4(6) = 87

 

Notice something else.....the difference between terms is   4, 8, 12, 16, 20, 24

 

Just for the heck of it, what would be the 8th term   ????

 

cool cool cool

 Apr 14, 2019
 #3
avatar-19 
-3

If we continue this same rule for the next term in the sequence then...

 

The 8th term would be: 8th term = 87 + 4(7) = 115

 

--7H3_5H4D0W

GAMEMASTERX40  Apr 22, 2019

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