I use Mathstackexchange frequently and usually I write down my question on Lyx and then copy to the website. However, I must insert a $ sign before and after every equation while I am writing it down with Lyx. Is there a smart way to do this without inserting it every time? Thank you. Here's how it looks like. As you can see I want to insert a $ symbol everytime.
Sort answer: Ctrl+M already insert
$ $ in LaTeX code.
$ is an active character that start/end the inline math mode.
$ is not a active character that will do nothing except print that symbol, and it will we exported to LaTeX as
\$ (the inactive symbol) in text mode or in math mode.
Therefore you cannot write in LyX
$...$ to make an equation like in LaTeX, except if you are in a TeX box, aka Evil Red Tex (ERT), using Ctrl+L but then you must work with LateX code in the red box, that do not show anything except what you write. Be careful with ERTs, some typo here can produce a fatal error (= no PDF preview).
To write in math mode in LyX use the blue ∑ butttom or Ctrl+M. This make a blue box, warning you that a math environment equivalent to
$...$ in LaTeX is already done, then you can write the equation with LaTeX commands as
\simeq but is showed the correspondent symbol
You can also write the equation "as is" in text mode (e.g.:
A \simeq B), then select the equation with the cursor and use Ctrl+M to convert to math mode (i.e.,
But as show your screenshot, all you equations are already in math mode, so you are trying is not only wrong, but also absolutely unnecessary.