The sum of the series 1 1+√2+ 1 √2+√3+ 1 √3+√4+… upto 15 terms is
JEE Main 2012 — Mathematics Algebra
2012mcqhard
The sum of the series 1+21+2+31+3+41+… upto 15 terms is
Official previous-year question
Held on 12 May 2012 · Verified 6 Jul 2026.
Options
A
1
B
2
C
3
D
4
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Solution
Given series is 1+21+2+31+3+41+…..nth term =n+n+11∴15th term =15+161 Thus, given series upto 15 terms is 1+21+2+31+3+41+……+15+161 This can be re-written as −11−2+−12−3+−13−4+……+−115−16 (By rationalization) =−1+2−2+3−3+4+…..−14+15−15+16=−1+16=−1+4=3 Hence, the required sum =3
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