JEE Main 2021 · MathsNumerical answerNumerical valueHardMulti-step

JEE Main 3 August 2021, Shift 1, Maths Q86

Question 86 of 90 in this shift, Maths question 26 of 30, Section B.

Let

f(x) = x + 1

and

g

be maps on

\mathbb{R}

and

h(n) = (g \circ f)(n+1) - (g \circ f)(n)

n \in \mathbb{N}

. Further,

h(1), h(2), h(3), h(4), \ldots\ldots

, is an A.P. and

h(25) = 53

h(101) = 205

. If

g(48) - g(2) = 100k

, then ‘

k

’ is equal to ________.

Official answer

NTA final key.

Chapter: Sequences and Series
Topic: AP and GP
Idea tested: AP General Term

Same idea in other shifts

Asked 7× in all

2 Apr 2026, Shift 2 · Q4Let $a_1, a_2, a_3, \ldots$ be an A.P. and $g_1, g_2, g_3, \ldots$ be an increasing G.P. If $a_1 = a_2 + g_2 = 1$ and $a_3 + g_3 = 4$ ,…MediumSingle correct
5 Apr 2026, Shift 2 · Q6Let $A_1, A_2, A_3, \dots\dots, A_{39}$ be 39 arithmetic means between the numbers 59 and 159. Then the mean of $A_{25}, A_{28}, A_{31}$ …EasySingle correct
25 Jul 2022, Shift 1 · Q24Let $a,\ b$ be two non-zero real numbers. If $p$ and $r$ are the roots of the equation $x^2-8ax+2a=0$ and $q$ and $s$ are the roots of the…HardNumerical value
27 Jun 2022, Shift 2 · Q6If $a_1, a_2, a_3\,......$ and $b_1, b_2, b_3......$ are A.P., and $a_1=2,\ a_{10}=3,\ a_1b_1=1=a_{10}b_{10}$ , then $a_4\,b_4$ is equal to -MediumSingle correct
4 Sep 2020, Shift 2 · Q57Let $a_1, a_2, \ldots, a_n$ be a given A.P. whose common difference is an integer and $S_n = a_1 + a_2 + \ldots + a_n$ . If…MediumSingle correct
6 Sep 2020, Shift 2 · Q56The common difference of the A.P. $b_1, b_2, \ldots, b_m$ is 2 more than the common difference of A.P. $a_1, a_2, \ldots, a_n$ . If…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.