I need help on the following problem:

The vectors v = $\displaystyle \begin{bmatrix} 0\\-4\\-8 \end{bmatrix} $, u = $\displaystyle \begin{bmatrix} -4\\8\\28+k \end{bmatrix}$, and w = $\displaystyle \begin{bmatrix} 2\\-4\\-14 \end{bmatrix} $ are linearly independent if and only if $\displaystyle k \neq ?$