/

Learn

Saturday, 31 October

/

JEE Main 2020 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 8 January 2020, Shift 1, Maths Q56

Question 56 of 75 in this shift, Maths question 6 of 25, Section A.

Let

f:\mathbf{R}\to\mathbf{R}

be such that for all

x\in\mathbf{R}

,

(2^{1+x}+2^{1-x})

,

f(x)

and

(3^x+3^{-x})

are in A.P., then the minimum value of

f(x)

is :

(1) $0$
(2) $2$
(3) $3$ Official answer
(4) $4$

Official answer

Option 3

NTA final key (Jan 2020).

Chapter: Sequences and Series
Topic: AP and GP
Idea tested: AM-GM Inequality Application

Same idea in other shifts

Asked 2× in all

5 Apr 2024, Shift 2 · Q8For $x \geq 0$ , the least value of $K$ , for which $4^{1+x}+4^{1-x}$ , $\frac{K}{2}$ , $16^x+16^{-x}$ are three consecutive terms of an A.P.,…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.