using LaTeX, type [tex]\frac{\,dy}{\,dx}[/tex] to get , [tex]\frac{d^2y}{\,dx^2}[/tex] to get , and [tex]\theta[/tex] to get . However, I prefer [tex]\vartheta[/tex] to get

You can find more tutorials and the such in the LaTeX Help part of the forums.

--Chris