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Saturday, 31 October

JEE Main 2021 · MathsMultiple choiceSingle correctMediumConceptual

JEE Main 26 February 2021, Shift 2, Maths Q72

Question 72 of 90 in this shift, Maths question 12 of 30, Section A.

Let F1(A,B,C)=(A∧∼B)∨[∼C∧(A∨B)]∨∼AF_1(A, B, C) = (A \wedge \sim B) \vee [\sim C \wedge (A \vee B)] \vee \sim A and F2(A,B)=(A∨B)∨(B→∼A)F_2(A, B) = (A \vee B) \vee (B \to \sim A) be two logical expressions. Then :
  1. (1)F1F_1 and F2F_2 both are tautologies
  2. (2)F1F_1 is a tautology but F2F_2 is not a tautology
  3. (3)F1F_1 is not a tautology but F2F_2 is a tautologyOfficial answer
  4. (4)Both F1F_1 and F2F_2 are not tautologies

Official answer

Option 3

NTA final key.

Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

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.