原式=
| −(b+c)•a |
| bc |
| −(a+c)•b |
| ac |
| −(a+b)•c |
| ab |
=-（
| ba+ca |
| bc |
| ab+cb |
| ac |
| ac+bc |
| ab |
=−(
| a |
| b |
| a |
| c |
| b |
| a |
| b |
| c |
| c |
| a |
| c |
| b |
=
| −(b+c) |
| a |
| −(a+c) |
| b |
| −(a+b) |
| c |
=
| a |
| a |
| b |
| b |
| c |
| c |
故选A．
| a2 |
| bc |
| b2 |
| ca |
| c2 |
| ab |
| −(b+c)•a |
| bc |
| −(a+c)•b |
| ac |
| −(a+b)•c |
| ab |
| ba+ca |
| bc |
| ab+cb |
| ac |
| ac+bc |
| ab |
| a |
| b |
| a |
| c |
| b |
| a |
| b |
| c |
| c |
| a |
| c |
| b |
| −(b+c) |
| a |
| −(a+c) |
| b |
| −(a+b) |
| c |
| a |
| a |
| b |
| b |
| c |
| c |