# Insert \$ before and after equation using Lyx

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.

• Welcome to TeX.SX! What do you mean? A keyboard shortcut, leaving it out completely? – TeXnician May 27 '17 at 11:37
• Thank you. Yes, exactly. I don't know if for example Lyx has some kind of built-in function that everytime I initialize an equation it would insert those "\$" signs. As far as I know there's something called macros but I don't know if this would solve my problem. – aadcg May 27 '17 at 11:44
• Do you start all your equations the same way? How should Lyx know when math starts other than `\$`? I do not really get it, but maybe there are some Lyx experts who can manage it. (Btw: Macros could also refer to TeX commands.) – TeXnician May 27 '17 at 11:46
• I don't know absolutely anything about Latex except using Lyx. When you want to insert an equation on Lyx you simple press CRTL + M. I will attach a photo to my post. – aadcg May 27 '17 at 11:49
• I don't get it either. I use LyX sometimes and in that case I don't need to introduce those `\$` myself. Entering math inline mode is enough (the CTRL+M shortcut you speak of). – Franck Pastor May 27 '17 at 12:23

Sort answer: Ctrl+M already insert `\$ \$` in LaTeX code.

In LaTeX `\$` is an active character that start/end the inline math mode. In Lyx, `\$` 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.,`A≃B`).