Answer
$-\hat{i}-3\hat{j}-9\hat{k}$
Work Step by Step
$u \times v=\begin{vmatrix}i&j&k\\3&-1&0\\0&-3&1\end{vmatrix} \\=[-1(1)-(0)(-3)] i+[0-(3)(1)]j+[ (3)(-3)-(-1)(0)]k$
or, $u \times v=(-1-0)i-3j+( -9-0) k$
Thus, $u \times v=-\hat{i}-3\hat{j}-9\hat{k}$
