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## #1 2013-03-08 12:55:17

infinitebrain
Member
Registered: 2008-07-01
Posts: 153

### Sequence question

Given the sequence

find k
I found the answer as 291, through a tedious guess and check method, but I'd like someone to explain in simpler terms how to find k.

Last edited by infinitebrain (2013-03-08 12:55:30)

The best thing about life is you don't know what to expect

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## #2 2013-03-08 13:16:56

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: Sequence question

Hi;

You can use differences to get the answer

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #3 2013-03-08 15:23:30

Stormtangent
Member
Registered: 2011-09-03
Posts: 33

### Re: Sequence question

Hi,

If you subtract consecutive terms, you see that you get:

Subtracting again, you get

You could find the quadratic.  However, another way is to realize that

, which, after solving, gives

Last edited by Stormtangent (2013-03-08 15:25:26)

"Have you ever had a dream that you were so sure was real? What if you were unable to wake from that dream? How would you know the difference between the dream world and the real world? "

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