SOLUTION: 7, 21, 8, 72, 9, ? 2, 7, 26, 101, 400, ?

Question 1096234: 7, 21, 8, 72, 9, ?
2, 7, 26, 101, 400, ?
Answer by Edwin McCravy(20056) (Show Source): You can put this solution on YOUR website!
7, 21, 8, 72, 9, ?

Start with 1st term 7.

Multiply 1st term 7 by 3¹, get 2nd term 21.

Add 1 to the 1st term, get 3rd term 8,

Multiply 3rd term 8 by 3², get 4th term 72.

Add 1 to the 3rd term, get 5th term 9,

Multiply 5th term 9 by 3³, get 5th term 243.  <--answer.

Add 1 to the 5th term, get 7th term 10,

Multiply 7th term 10 by 3⁴, get 8th term 810.

--------------------

2, 7, 26, 101, 400, ?


Start with 1st term 2

Multiply 1st term 2 by 4, getting 8, then subtracting 1, 
      getting 2nd term 7.

Multiply 2nd term 7 by 4, getting 28, then subtracting 2, 
      getting 3rd term 26. 

Multiply 3rd term 26 by 4, getting 104, then subtracting 3, 
      getting 4th term 101.

Multiply 4th term 101 by 4, getting 404, then subtracting 4, 
      getting 5th term 400.

Multiply 5th term 400 by 4, getting 1600, then subtracting , 
      getting 6th term 1595.  <---answer

Edwin

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