$\bar a\,\,.\,\,\left\{ {\left( {\bar b\, + \,\bar c} \right)\, \times \,\left( {\bar a\, + \,\bar b\, + \,\bar c} \right)} \right\}\,\,\,$
$ = \,\,\bar a\,.\,\{ \bar b\, \times \,\bar a\, + \,\bar b\, + \,\bar b\, \times \,\bar c\, + \,\bar c\, \times \,\bar a\, + \,\bar c\, \times \,\bar b\, + \,\bar c\, \times \,\bar c\} $
$\,\,\, = \,\,\bar a\,.\,\,\left\{ {\bar b\, \times \,\bar a\, + \,\bar b\, \times \,\bar c\, + \,\bar c\, \times \bar a\, + \,\bar c\, \times \,\bar b} \right\}\,$
$ = \,\,\,\,\bar a\,.\,\left( {\bar b\, \times \,\bar a} \right)\, + \,\bar a\left( {\bar b\, \times \,\bar c} \right)\, + \,\bar a\,\left( {\bar c\, \times \,\bar a} \right)\, + \,\bar a\,.\,\left( {\bar c\, \times \,\bar b} \right)\,$
$=\,\,\left[ {\bar a\,\bar b\,\bar a} \right]\, + \,\,\left[ {\bar a\,\bar b\,\bar c} \right]\,\, + \,\,\left[ {\bar a\,\bar c\,\bar a} \right]\,\, + \,\,\left[ {\bar a\,\,\bar c\,\,\bar b} \right]$
$ = \,\,\left[ {\bar a\,\bar b\,\bar c} \right]\, + \,\,\left[ {\bar a\,\,\bar c\,\bar b} \right]\,\,\,\,\, $
$= \,\,\left[ {\bar a\,\bar b\,\bar c} \right]\, - \,\,\left[ {\bar a\,\bar b\,\bar c} \right]\,\,\, $
$= \,\,0$