6. Show that the given vector is in the span of S:
a) $\begin{bmatrix} 1 \ 0 \ 1 \end{bmatrix}$, $S = \left\{ \begin{bmatrix} 1 \ -1 \ 0 \end{bmatrix}, \begin{bmatrix} 0 \ 0 \ 1 \end{bmatrix}, \begin{bmatrix} 1 \ 1 \ 0 \end{bmatrix} \right\}$
b) $[2, -1, 1]^t$, $S = \left\{ [1, 0, 2]^t, [-1, 1, 1]^t \right\}$.
