If [→a→b→c]=→k, where k≠0, then [(→b×→c)×(→c×→a)(→c×→a)×(→a×→b)(→a×→b)×(→b×→c)]=
If →a,→b and →c are three non-coplanar vectors, then (→a+→b+→c)⋅[(→a+→b)×(→a+→c)] equals