JEE Main 2021 · MathsMultiple choiceSingle correctMediumCalculation

JEE Main 27 August 2021, Shift 1, Maths Q63

Question 63 of 90 in this shift, Maths question 3 of 30, Section A.

If the matrix

A=\begin{pmatrix}0 & 2\\ K & -1\end{pmatrix}

satisfies

A(A^3+3I)=2I

, then the value of

K

is :

(1) $-\frac{1}{2}$
(2) $-1$
(3) $\frac{1}{2}$ Official answer
(4) $1$

Official answer

Option 3

NTA final key.

Chapter: Matrices
Topic: Matrix Multiplication
Idea tested: Cayley-Hamilton Theorem Application

Same idea in other shifts

Asked 10× in all

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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.