1.
If a=2i^+3j^k^\vec{a} = 2\hat{i} + 3\hat{j} - \hat{k}, b=i^+2j^4k^\vec{b} = -\hat{i} + 2\hat{j} - 4\hat{k} and c=i^+j^+k^\vec{c} = \hat{i} + \hat{j} + \hat{k}, then (a×b)(a×c)=(\vec{a} \times \vec{b}) \cdot (\vec{a} \times \vec{c}) =