Enclose the formula between backslash dollar if you need an inline formula, for example like this one \$\Phi = BA\$, placed in a normal conversation.

Sometimes I use

https://www.codecogs.com/latex/eqneditor.php as an online editor, good to see the rendered formula, because the forum shows the rendered formula only after posting, it does not render it at preview.

LATER EDIT: Found an older post with a clean example in it.

Latex enclosed by backslash dollar will render it inline, when enclosed by double dollar will render centered, on a new line.

Example:

`From Faraday's induction law, the induced voltage \$V\$ in an \$N\$ turns coil will be:`

$$V = -N\frac{\vartriangle \Phi}{\vartriangle t}$$

where \$\Phi\$ is the magnetic flux

From Faraday's induction law, the induced voltage \$V\$ in an \$N\$ turns coil will be:

$$V = -N\frac{\vartriangle \Phi}{\vartriangle t}$$

where \$\Phi\$ is the magnetic flux

The Latex render will be seen only after posting the message, not at preview.