Formulas

<tex> \documentclass{article} \usepackage{amsmath} \usepackage{upgreek} \begin{document}

\begin{align} a &= b+c+d \\ x &= y+z \end{align}

\begin{equation} \begin{vmatrix} x&y\\z&v \end{vmatrix} \begin{bmatrix} x&y\\z&v \end{bmatrix} \begin{pmatrix} x&y\\z&v \end{pmatrix} \end{equation}

\begin{equation} y=\begin{cases} -x,& x\leq 0 \\ x,& x>0 \end{cases} \end{equation}

\begin{equation} x=\frac{-b\pm\sqrt{b^2-4ac}}{2a} \end{equation}

\begin{equation}

   f(x) = \dfrac{1}{2\uppi}\int ^{\infty}_{-\infty}\hat{F}(k)\mathrm{e}^{\mathrm{i}kx}\mathrm{d}k \tag{ISO style}

\end{equation}

\begin{equation}

   f(x) = \dfrac{1}{2\pi}\int ^{\infty}_{-\infty}\hat{F}(k)e^{ikx}dk \tag{Conventional style}

\end{equation}

\end{document} </tex>