common patterns:

\frac{1}{2} = {$\frac{1}{2}$}; \times = {$\times$};
a^{b} = {$a^{b}$}; a_{b} = {$a_{b}$}; \vec{x} = {$\vec{x}$};
^{\circ}\mathrm{C} = {$^{\circ}\mathrm{C}$};
\int_a^b f(x) dx = {$\int_a^b f(x) dx$};
\sqrt[n]{x} = {$\sqrt[n]{x}$};
\alpha = {$\alpha$}; \beta = {$\beta$}; \gamma = {$\gamma$};
\left| \‌begin{array}{cc}a &b\\d & e\end{array} \right| {$\left| \begin{array}{cc}a &b\\d & e\end{array} \right|$}