JEE Main 2021MathematicsMatricesEasyMCQ

JEE Main 2021 — Matrices Question with Solution

JEE Main 2021 (27 Jul Shift 1)

Question

LetA=12-14.  If A-1=αI+βA, α,β∈R, I is a 2×2 identity matrix, then 4α-β is equal to :

Choose an option

Show full solutionCorrect option: D
Correct answer
D4

Step-by-step explanation

Given,

A=12-14⇒A=6

So, A-1=adjAA=164-211=23-131616

Here, 23-131616=α00α+β2β-β4β

α+β=23β=-16⇒α=23+16=56

Hence, 4α-β=41=4

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About this question

This is a previous-year question from JEE Main 2021, covering the Matrices chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.