Equation

Here is some regularly sized text for comparison. $E=m{c}^2$

$x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}/h$

$\mathrm{\Phi }(x)=\frac{1}{\sqrt{2\pi }}\underset{-\mathrm{\infty }}{\overset{x}{\int }}{e}^{-t^2/2}\mathrm{d}t$