If for the matrix, A = 1 - α α β ,   A A T = I 2 , then the value of α 4 + β 4…

If for the matrix, A=1-ααβ, AAT=I2, then the value of α4+β4 is :
  1. 3
  2. 1
  3. 2
  4. 4

Solution

A=1-ααβ  AAT=I2

1-ααβ1α-αβ=1001

1+α2α-αβα-αβα2+β2=1001

1+α2=1 & α2+β2=1

α2=0 & β2=1

 α4=0 & β4=1

 α4+β4=1

Asked in: JEE Main 2021 (25 Feb Shift 2)

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