Learn

Saturday, 31 October

JEE Main 2022 · MathsNumerical answerNumerical valueHardCalculation

JEE Main 28 June 2022, Shift 2, Maths Q25

Question 25 of 90 in this shift, Maths question 25 of 30, Section B.

Let for n=1,2,…,50n=1, 2, \ldots, 50, SnS_n be the sum of the infinite geometric progression whose first term is n2n^2 and whose common ratio is 1(n+1)2\frac{1}{(n+1)^2}. Then the value of 126+∑n=150(Sn+2n+1−n−1)\frac{1}{26}+\sum_{n=1}^{50}\left(S_n+\frac{2}{n+1}-n-1\right) is equal to __________.

Official answer

41651

NTA final key.

Idea tested
Infinite GP Sum

Same idea in other shifts

Asked 15× in all
  1. 4 Apr 2026, Shift 2 · Q7Let α=14+18+116+…∞\alpha=\frac14+\frac18+\frac1{16}+\ldots\infty and β=13+19+127+…∞\beta=\frac13+\frac19+\frac1{27}+\ldots\infty. Then the value of…EasySingle correct
  2. 6 Apr 2024, Shift 2 · Q16Let ABCABC be an equilateral triangle. A new triangle is formed by joining the middle points of all sides of the triangle ABCABC and the…MediumSingle correct
  3. 9 Apr 2024, Shift 2 · Q7Let a,ar,ar2,…a, ar, ar^2, \ldots be an infinite G.P. If ∑n=0∞arn=57\sum_{n=0}^{\infty}ar^n=57 and ∑n=0∞a3r3n=9747\sum_{n=0}^{\infty}a^3r^{3n}=9747, then a+18ra+18r is…MediumSingle correct
  4. 15 Apr 2023, Shift 1 · Q24If the sum of the series…HardNumerical value
  5. 27 Jul 2022, Shift 2 · Q7Let the sum of an infinite G.P., whose first term is a and the common ratio is r, be 5. Let the sum of its first five terms be…MediumSingle correct
  6. 26 Jun 2022, Shift 2 · Q3If A=∑n=1∞1(3+(−1)n)nA = \sum_{n=1}^{\infty} \frac{1}{(3 + (-1)^n)^n} and B=∑n=1∞(−1)n(3+(−1)n)nB = \sum_{n=1}^{\infty} \frac{(-1)^n}{(3 + (-1)^n)^n}, then AB\frac{A}{B} is…MediumSingle correct
  7. 27 Jun 2022, Shift 1 · Q3If x=∑n=0∞anx=\sum_{n=0}^{\infty} a^n, y=∑n=0∞bny=\sum_{n=0}^{\infty} b^n, z=∑n=0∞cnz=\sum_{n=0}^{\infty} c^n, where a, b, c are in A.P. and ∣a∣<1|a|<1, ∣b∣<1|b|<1,…MediumSingle correct
  8. 26 Aug 2021, Shift 1 · Q67If the sum of an infinite GP a,ar,ar2,ar3,…a, ar, ar^2, ar^3, \ldots is 15 and the sum of the squares of its each term is 150, then the sum of…MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.