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Algebra

Scorching goIITian

Joined:	9 Jun 2008
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30 Jun 2009 22:31:29 IST

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325

find the nth term

Engineering Entrance , JEE Main , JEE Advanced , Mathematics , Algebra

find the nth term of the series 2.2+4.2²+7.2³+11.2³+16.2^5................................

Comments (6)

hurricane

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30 Jun 2009 22:40:26 IST

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(2^n)(n^2+n+2)/2

sankar

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30 Jun 2009 22:41:13 IST

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hey i donno the ans can u give me the soln.

sankar

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30 Jun 2009 22:43:57 IST

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harini do me a favor.And i will rate u if u have given me the ans.

hurricane

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30 Jun 2009 22:48:18 IST

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ok fine bro,

2^n factor in the ans is obvious.

just look at the other part.

2,4,7,11,16................

2+2

2+2+3

2+2+3+4 etc

2+3+4... can be added up by the summation formula if we add and subtract 1

so{ 2+[(n^2+n-2)/2]}2^n

upon simplification u get the ans

sankar

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30 Jun 2009 22:52:28 IST

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have u check it for 4.its not working am i rite.

hurricane

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30 Jun 2009 22:55:45 IST

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if the 4 th term is not with 2^4 it doesn't seem to be a sequence..................

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