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Question: Answered & Verified by Expert
If A=15λ10, A-1=αA+βI and α+β=-2, then 4α2+β2+λ2 is equal to :
MathematicsMatricesJEE MainJEE Main 2023 (08 Apr Shift 2)
Options:
  • A 12
  • B 19
  • C 14
  • D 10
Solution:
1132 Upvotes Verified Answer
The correct answer is: 14

Given,

A=15λ10, A-1=αA+βI and α+β=-2,

Now solving by using characteristic equation, we get
|A-k|=01-k5λ10-k=0

k2-11k+10-5λ=0

A2-11A+(10-5λ)I=0 {by putting k=A}

  A-1=110-5λ(-A+11I)

Now on comparing with A-1=αA+βI we get,

α=-110-5λ, β=1110-5λ

And given,

α+β=-2λ=3, α=15, β=-115

Hence, the value of 4α2+β2+λ2=14

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