Preview renders latex but posted message does not

[Stephen Tashi]

In replying to the thread https://www.physicsforums.com/threa...n-arithmetic-progression.997190/#post-6429582 I exerted myself to write the binomial coefficients in Latex. After they displayed properly in the Preview function of the editor, I Posted the thread and the LaTex vanished.

When I Edited the message, the Latex was gone and only a text version of the algebra appeared. So I hastily edited the text algebra by adding parenthesis, so it made sense. I was going to advise the OP to use LaTex, but after this experience, I can see why he/she might not want to.

 

[berkeman]

It looks like it worked in your repost. What did you do differently?

I'm having trouble getting the forum's LaTex to work.

I'll try again:

For example:

$\frac{\frac{n!}{(n-(r+1))!(r+1)!} }{\frac{n!}{(n-r)! r!} }$

$= \frac{(n-r)!}{(n-(r+1))!} \frac{r!}{(r+1)!)}$

$= (n-r) \frac{1}{(r+1)}$

 

[Ibix]

I've had this happen to me. I think you have to have previewed something with LaTeX, and then someone else replies to the thread (anuttarasammyak in this case, I suspect - perhaps @Stephen Tashi can confirm if he saw that post before starting to reply).

I think it only happens with the rich text editor, but I'm not 100% certain on that. It's also possible that the "intruding" reply needs LaTeX in it.

 

[Stephen Tashi]

I didn't notice doing anything different in my second reply - except that I copied the LaTex in the preview to the clipboard in case it vanished again!

The message by @anuttarasammyak was already showing when I began composing my first reply.