Question

Se u = 3i - j - 2k, v = 2i + 4j - k e é = -i + k podemos afirmar que u x (v x w)

Answer 1

$u = 3i -j -2k = (3;-1;-2)\\\\v = 2i+4j-k = (2;4;-1)\\\\ w=-i+k = (-1;0;1)$

resolvendo 
$V_XW = \left[\begin{array}{ccc}i&j&k\\2&4&-1\\-1&0&1\end{array}\right] = (4i,-1j,4k)$

agora u x (vxw)

$U_X(V_XW) = \left[\begin{array}{ccc}i&j&k\\3&-1&-2\\4&-1&4\end{array}\right] = (-6,-20,1)$