Math Accents, Over and Underscripts

Note: click with the right mouse button on any WebEQ equation to bring up a font size control panel.

x'=\bar{x} + \tilde{x}^2 + \hat{x} + \vec{x} + \dot{x} + \ddot{x}

\widetilde{\mathrm{SL}(2, \mathbf{C})} =

\overset{\text{$n$ terms}}{\overbrace{K_1 + \cdots + K_n}}

More information on these commands may be found in Mathematical Expressions: Accents of the WebTeX documentation.