JEE Main 2019MathematicsMatricesMediumMCQ

JEE Main 2019 — Matrices Question with Solution

JEE Main 2019 (12 Apr Shift 1)

Question

If B=52α1021α3-1 is the inverse of a 3×3 matix A, then the sum of all values of α for which  detA+1=0, is:

Choose an option

Show full solutionCorrect option: B
Correct answer
B1

Step-by-step explanation

Since, A=-1
Hence, B=1|A|=-1
⇒B=5-5-2α-α-2α
           =2α2-2α-25

1+A=0
α2-α-12=0
Sum =1

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About this question

This is a previous-year question from JEE Main 2019, 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.