Can someone help me figure out a recursive formula for this?  TOPIC_SOLVED

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Can someone help me figure out a recursive formula for this?

Postby noobzilla on Thu Oct 15, 2009 10:51 pm

I GIVE UP, seriouosly i've tried so many ways to figure this out but i just can't seem to see the pattern :oops: :oops: :oops:

Find the next two numbers in each sequence.

A) -1, 1 , 3 , 7 , 15 , ______ , _______

B) 3, 1, 2 , -1 , 3 , -4 , ______, _______

C) 16, 24, 36 , 54 , 81, ______, ______


just to show you I'm really trying hard, the next two terms for the second sequences are as follows (according to my calculations of course):

3, 1, 2 , -1 , 3 , -4 , 7, -11, 18
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Postby stapel_eliz on Fri Oct 16, 2009 12:57 pm

For some general techniques, try here. :wink:

noobzilla wrote:Find the next two numbers in each sequence.

A) -1, 1 , 3 , 7 , 15 , ______ , _______

What are the differences between the terms? What is 2*2? What is 2*4?

noobzilla wrote:B) 3, 1, 2 , -1 , 3 , -4 , ______, _______

What are the differences? What is the sum of |-2| and |1|? What is the sum of |1| and |-3|? (I get the same next terms as you do, by the way.)

noobzilla wrote:C) 16, 24, 36 , 54 , 81, ______, ______

What are the differences? What is the value of 2*22? What is the value of 3*22? What is the value of 2*32? What is the value of 3*32?

:popcorn:
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Re: Can someone help me figure out a recursive formula for this?

Postby noobzilla on Sat Oct 17, 2009 7:36 pm

THANK YOU SO MUCHH!!

I get it all now, thnx a lot, for the last two i was able to find formulas that work, just like the one you hinted me to see, it works both ways, but i'll use yours cause it's simpler, and the first one, GOD I swear I couldn't see the pattern in it :roll:

But Thanks Again, I'm very grateful for your help! :) :) :)
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