मराठी

Show that A′A and AA′ are both symmetric matrices for any matrix A.

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प्रश्न

Show that A′A and AA′ are both symmetric matrices for any matrix A.

बेरीज
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उत्तर

Let P = A'A

⇒ P' = (A'A)'

⇒ P' = A'(A')'   .....[(AB') = B'A']

⇒ P' = A'A   ......[∵ (A')' = A]

⇒ P' = P

Hence, A'A is a symmetric matrix.

Now, Let Q = AA'

⇒ Q' = (AA')' 

⇒ Q' = (A')A'   .....[(AB)' = B'A']

⇒ Q' = AA'  ......[∵ (A')' = A]

⇒ Q' = Q

Hence, AA' is also a symmetric matrix.

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पाठ 3: Matrices - Exercise [पृष्ठ ५६]

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