Let A = 1 2 - 1 4 . If A - 1 = α I + β A ,   α , β ∈ R ,   I is a 2…

LetA=12-14.  If A-1=αI+βA, α,βR, I is a 2×2 identity matrix, then 4α-β is equal to :
  1. 5
  2. 83
  3. 2
  4. 4

Solution

Given,

A=12-14A=6

So, A-1=adjAA=164-211=23-131616

Here, 23-131616=α00α+β2β-β4β

α+β=23β=-16α=23+16=56

Hence, 4α-β=41=4

Asked in: JEE Main 2021 (27 Jul Shift 1)

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