C$\left[ {\begin{array}{*{20}{c}}{\,\,2}&{\,\,1}&{ - 1}\\{ - 2}&{ - 1}&{\,\,1}\\{\,\,4}&{\,\,2}&{ - 2}\end{array}} \right]$
c
(c)$\left[ {\begin{array}{*{20}{c}}{\,\,1}\\{ - 1\,}\\{\,\,2}\end{array}} \right]\,\,[\begin{array}{*{20}{c}}2&1&{ - 1}\end{array}] = \left[ {\begin{array}{*{20}{c}}2&1&{ - 1}\\{ - 2\,\,\,}&{ - 1\,\,\,}&{\,\,1}\\4&2&{ - 2}\end{array}} \right]$.