$\large \begin{align} \deriv{x}{t} &= 2x - y \\ \deriv y t &= x + y \\ \let \vec x &= \mat{x\\y} \\ \deriv {\vec{x}}{t} &= \mat{2 &-1\\1& 1} \vec x \\ \end{align} $ >[!note] > [[Jacobian]] MENTIONED