JEE Main 2023 · MathsMultiple choiceSingle correctMediumMulti-step

JEE Main 6 April 2023, Shift 1, Maths Q3

Question 3 of 90 in this shift, Maths question 3 of 30, Section A.

Let

A=[a_{ij}]_{2\times2}

, where

a_{ij}\neq0

for all i, j and

A^2=I

. Let

a

be the sum of all diagonal elements of

A

and

b=|A|

. Then

3a^2+4b^2

is equal to

(1)3
(2)4Official answer
(3)7
(4)14

Official answer

Option 2

NTA final key.

Chapter: Matrices
Topic: Matrix Multiplication
Idea tested: Involutory Matrix Properties

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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 42 of the 174 JEE Main shifts held from 2017 to 2026.