Express in the form $Z = VDU^{T}$ (specifying your choices of $U$, $V$ and $D$) for the matrices $$Z_{1} = \begin{pmatrix} 0 & 1 \\ 2 & 0 \end{pmatrix} \quad \text{and} \quad Z_{2} = \begin{pmatrix} 0 & 1 \\ -2 & 0 \end{pmatrix}.$$