JEE Main 2015MathematicsSequences and SeriesHardMCQ

JEE Main 2015 — Sequences and Series Question with Solution

JEE Main 2015 (04 Apr)

Question

The sum of first 9 terms of the series 131+13+231+3+13+23+331+3+5+... is

Choose an option

Show full solutionCorrect option: C
Correct answer
C96

Step-by-step explanation

Given, 131+13+231+3+13+23+331+3+5+...

∴ Tn=13+23+...+n31+3+...+2n-1

=n2n+124n2

=n+124

Sum of 9 terms

=∑n=19n+124

=1422+32+...+102
=1412+22+...+102-12   

= 1 4 1 0 · 1 1 · 2 1 6 - 1      

= 1 4 3 8 4 = 9 6

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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.