Let \(\mathbf {A}\) be a square symmetric matrix.
- Show that if \(\mathbf {A}^{k}\) is the identity matrix for some \(k \ge 2\) then \(\mathbf {A}^{2}\) is the identity matrix.
- Show that if \(\mathbf {A}^{k}\) is the zero matrix for some \(k \ge 2\) then \(\mathbf {A}\) is the zero matrix.