Math Is Fun Forum

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)

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bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Sequence question

Hi;

You can use differences to get the answer

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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)

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