# Latex Formula

1. May 14, 2008

### temaire

How do you write the permutation and combination formulas using latex. This is the best I can do:

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

2. May 14, 2008

### cristo

Staff Emeritus
You mean like this: $$n \choose r$$ or $$^n\mathrm{C}_r$$ ?

Last edited: May 14, 2008
3. May 14, 2008

### temaire

Yes, that's what I meant, but I am used to writing down like this:

http://img88.imageshack.us/img88/7682/formula2nj1.png [Broken]

Last edited by a moderator: May 3, 2017
4. May 14, 2008

### cristo

Staff Emeritus
Ok, how about this then: $$_n\mathrm{C}_r \hskip5mm _n\mathrm{P}_r$$

5. May 14, 2008

### temaire

Thanks, that's what I needed.

6. May 14, 2008

### temaire

Out of curiosity, are you good at perms. and combs.? Because I have a question on the the Precalc. forum that hasn't been answered yet. If not, it's ok, because I can wait.