JEE Main 2017MathematicsSequences and SeriesHardMCQ

JEE Main 2017 — Sequences and Series Question with Solution

JEE Main 2017 (08 Apr Online)

Question

If the sum of the first n terms of the series 3+ 75+ 243+ 507+… is 4353, then n equals:

Choose an option

Show full solutionCorrect option: B
Correct answer
B 15

Step-by-step explanation

3 1+25+ 81+ 169+…=4353

3 1+5+9+13+…Tn=4353

= 3×n22+n-14=4353

=2n+4n2-4n=870

=4n2-2n-870=0

=2n2-n-435=0

n=1± 1+4×2×4354

=1±594      ∵n is +ve

∴n=1+594=15 

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About this question

This is a previous-year question from JEE Main 2017, 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.