JEE Main 2015MathematicsSequences and SeriesHardMCQ

JEE Main 2015 — Sequences and Series Question with Solution

JEE Main 2015 (11 Apr Online)

Question

If ∑ n=1 5 1nn+1n+2n+3=k3,  then k is equal to:

Choose an option

Show full solutionCorrect option: A
Correct answer
A55336

Step-by-step explanation

Tn=13n+3-nn(n+1)(n+2)(n+3)

=131n(n+1)(n+2)-1n+1n+2n+3

∑ n=1 5 T n = 1311·2·3-12·3·4+12·3·4-13·4·5…+15·6·7-16·7·8

=1316-16·56 

=1356-1336

=553336=k3

⇒k=55336

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About this question

This is a previous-year question from JEE Main 2015, covering the Sequences and Series chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.