Does a symmetric matrix $A^2$ imply a symmetric $A$?
Any help would be much appreciated.
No. $$ \left( \begin{array}{cc} 0 & 1 \\ 2 & 0 \end{array} \right) \left( \begin{array}{cc} 0 & 1 \\ 2 & 0 \end{array} \right) = \left( \begin{array}{cc} 2 & 0 \\ 0 & 2 \end{array} \right) $$ which is symmetric.
HINT:
No, for instance take $A$ antisymmetric.
Hint: No, for instance some nilpotent matrices.
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No. $$ \left( \begin{array}{cc} 0 & 1 \\ 2 & 0 \end{array} \right) \left( \begin{array}{cc} 0 & 1 \\ 2 & 0 \end{array} \right) = \left( \begin{array}{cc} 2 & 0 \\ 0 & 2 \end{array} \right) $$ which is symmetric.