JEE Main 2020 · MathsNumerical answerNumerical valueMediumMulti-step

JEE Main 8 January 2020, Shift 1, Maths Q72

Question 72 of 75 in this shift, Maths question 22 of 25, Section B.

The number of all

3\times3

matrices A, with enteries from the set

\{-1,0,1\}

such that the sum of the diagonal elements of

AA^T

is 3, is ______.

Official answer

672.00

NTA final key (Jan 2020).

Chapter: Matrices
Topic: Matrix Multiplication
Idea tested: Trace of A times A Transpose

Same topic in other shifts

All Matrix Multiplication questions

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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.