Rajasthan BoardEnglish MediumSTD 12 ScienceMATHSMATRICES5 Marks
Question
Show that A′A and AA′ are both symmetric matrices for any matrix A.
✓
Answer
Let P = A'A
$\therefore$ P' = (AA')'
= A'(A')' $[\because$ (AB')' = BA'$]$
= A'A = P
So, A’A is symmetric matrix for any matrix A.
Similarly, let Q = AA’
$\therefore$ Q' = (AA')' = (A')'(A)'
= A(A')' = Q
So, AA’ is symmetric matrix for any matrix A.
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