Hallo,
Du rechnest nicht 0·s sondern 0 + s:
\( \vec{a}+\vec{b}=\left(\begin{array}{c}-1 \\ 0 \\ 3\end{array}\right)+\left(\begin{array}{l}0 \\ s \\ 1\end{array}\right)=\left(\begin{array}{c}-1 \\ s \\ 4\end{array}\right) \)
\( \vec{a}-\vec{b}=\left(\begin{array}{c}-1 \\ 0 \\ 3\end{array}\right)-\left(\begin{array}{l}0 \\ s \\ 1\end{array}\right)=\left(\begin{array}{c}-1 \\ -s \\ 2\end{array}\right) \)
Gruß, Silvia