\( \begin{aligned} \sum \limits_{k=1}^{n+1}(-1)^{k} k^{2} & =(-1)^{n+1}(n+1)^{2}+\sum \limits_{k=1}^{1}(-1)^{k} k^{2} \\ & \\ & =(-1)^{n+1}(n+1)^{2}+(-1)^{n}\left(\begin{array}{c} n+1 \\ 2 \end{array}\right) \end{aligned} \)
\(=(-1)^{n+1} \cdot ( (n+1)^2 + (-1) \cdot\begin{pmatrix} n+1\\2 \end{pmatrix} ) \)
\(=(-1)^{n+1} \cdot ( n^2 + 2n +1 - \frac{(n+1)n}{2} ) \)
\(=(-1)^{n+1} \cdot ( \frac{2n^2 + 4n +2}{2} - \frac{n^2 + n}{2} ) \)
\(=(-1)^{n+1} \cdot \frac{n^2 + 3n +2}{2} \)
\(=(-1)^{n+1} \cdot \frac{(n+2)(n+1)}{2} \)
\( =(-1)^{n+1}\left(\begin{array}{c}n+2 \\ 2\end{array}\right) \)