SOLUTION: What are the next three terms in each sequence? 9,109,209,309,409 1/2, 1/2,3/8, 1/4, 5/32

Algebra ->  Sequences-and-series -> SOLUTION: What are the next three terms in each sequence? 9,109,209,309,409 1/2, 1/2,3/8, 1/4, 5/32      Log On


   



Question 694948: What are the next three terms in each sequence?
9,109,209,309,409
1/2, 1/2,3/8, 1/4, 5/32

Found 2 solutions by Edwin McCravy, MathLover1:
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
9, 109, 209, 309, 409

Consider the first term 9, to be written 009, then we have:

009, 109, 209, 309, 409

Then the last two digits of them all are 09 and the
first digits go 0,1,2,3,4.  So the next three are, 
of course 5,6,7.  Putting 09 after them we get:

009, 109, 209, 309, 409, 509, 607, 709.

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

1%2F2, 1%2F2, 3%2F8, 1%2F4, 5%2F32

We notice that all the denominators are powers of 2.

We notice that the 1st term has a numerator of 1 and a denominator of 2%5E1.
We notice that the 3rd term has a numerator of 3 and a denominator of 2%5E3.
We notice that the 5th term has a numerator of 5 and a denominator of 2%5E5.

So the 1st, 3rd, and 5th terms are 1%2F2%5E1, 3%2F2%5E3, and 5%2F2%5E5 

That's a pattern with the 3 odd-numbered terms, so for the odd-numbered
terms, we have the pattern n%2F2%5En where n is odd 1, 3, and 5.

So we wonder if the two even numbered terms might follow
the same pattern. 

They would if the 2nd term, 1%2F2, were 2%2F2%5E2, 
and the 4th term, 1%2F4, were 4%2F2%5E4.  Sure enough
they are, since 2%2F2%5E2 = 2%2F4 = 1%2F2, and
4%2F2%5E4 = 4%2F16 = 1%2F4

So we have the pattern.  The nth term is n%2F2%5En

So the 6th term is 6%2F2%5E6 = 6%2F64 = 3%2F32,
the 7th term is 7%2F2%5E7 = 7%2F128, and
the 8th term is 8%2F2%5E8 = 8%2F256 = 1%2F32

1%2F2, 1%2F2, 3%2F8, 1%2F4, 5%2F32, red%283%2F32%29, red%287%2F128%29, red%281%2F32%29.

Edwin

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

1.
Note: starting with 9, you add 100 to get 109, than 109%2B100=209...
so for 9, 109, 209, 309, 409,the next three terms are
509, 609, 709
2.
Note: a%5Bn%5D=+n%2F2%5En
so, for 1%2F2, 1%2F2, 3%2F8,+1%2F4, 5%2F32
the next three terms are
3%2F32, 7%2F128, 1%2F32