a
\(\left( {\mathop {\,{\text{A}}}\limits^ \to \, + \;\mathop {\text{B}}\limits^ \to } \right)\,.\,\,\left( {\mathop {\,{\text{A}}}\limits^ \to \,\, \times \;\,\mathop {\text{B}}\limits^ \to \,} \right)\,\, = \,\,\mathop {\,{\text{A}}}\limits^ \to \,.\,\left( {\mathop {\,{\text{A}}}\limits^ \to \, \times \;\mathop {\text{B}}\limits^ \to } \right)\,\, + \;\;\mathop B\limits^ \to \,\,.\,\,\left( {\mathop {\,{\text{A}}}\limits^ \to \, \times \;\mathop {\text{B}}\limits^ \to } \right)\,\,\)
\(= \,\,0\,\, + \;\,0\,\, = \,\,0\)