JEE Main 2021 · MathsNumerical answerNumerical valueHardMulti-step

JEE Main 22 July 2021, Shift 2, Maths Q82

Question 82 of 90 in this shift, Maths question 22 of 30, Section B.

Let

\mathrm{A}=\begin{bmatrix}0&1&0\\1&0&0\\0&0&1\end{bmatrix}

. Then the number of

3\times3

matrices

\mathrm{B}

with entries from the set

\{1, 2, 3, 4, 5\}

and satisfying

\mathrm{AB}=\mathrm{BA}

is ________.

Official answer

3125

NTA final key.

Chapter: Matrices
Topic: Matrix Multiplication
Idea tested: Non-commutativity Property

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