A is a square matrix of order 3 × 3 . The matrices A , 4 A - 1 , A T all have the same value of the determinant. If a d j A = 2 A T , then 3 A - 1 is equal to

Question

A is a square matrix of order 3 × 3 . The matrices A , 4 A - 1 , A T all have the same value of the determinant. If a d j A = 2 A T , then 3 A - 1 is equal to, 3 2, 9 4, 27 8, 3

MARKS App · Accepted Answer

A = 4 A - 1 = A T ⇒ A = 64 A = A ⇒ A 2 = 64 ⇒ A = 8 or - 8 ∵ a d j A = 2 A T ⇒ a d j A = 2 A T ⇒ A 2 = 8 A ⇒ A = 0,8 ⇒ A = 8 So, 3 A - 1 = 27 A = 27 8

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