vector{M_(1)M_(o)}=(2-1;3-1;8-2)=(1;2;6)
vector{M_(2)M_(o)}=(2-(-1);3-1;8-3)=(3;2;5)
vector{M_(3)M_(o)}=(2-2;3-(-2);8-4)=(0;5;4)
V=|(vector{M_(1)M_(o)}, vector{M_(2)M_(o)},vector{M_(3)M_(o)})|
(vector{M_(1)M_(o)}, vector{M_(2)M_(o)},vector{M_(3)M_(o)})=[m]\begin {vmatrix} 1&2&6\\3&2&5\\0&5&4\end {vmatrix}[/m]
Раскрываем определитель
(vector{M_(1)M_(o)}, vector{M_(2)M_(o)},vector{M_(3)M_(o)})=8+0+90-0-25-24=50
V=|50|=50