# Using \emph and a subscript

How would I go about adding a subscript to a symbol I'm defining from an equation. For example I have an equation

E_m = \alpha_m x + y

How can I then do something like \emph \alpha\textsubscript{m}

The above gives me errors and I can't figure out how to correct this.

-
why don't you just set the substring as math? i.e., $\alpha_m$ -- \emph usually sets its argument in italic, and that's the usual math style. –  barbara beeton May 2 '12 at 15:45
Such a formula should be typed as $$E_{m}=\alpha_{m}x+y$$: TeX will take care of the details of math mode. –  egreg May 2 '12 at 15:45
Welcome to TeX.SE. Do you want the subscript in italic, or roman? The usual $E_{m} = \alpha_{m} x + y$ will give you italics, and $E_m = \alpha_{\mathrm{m}} x + y$ will give you a roman subscript. –  Peter Grill May 2 '12 at 16:44
That's brilliant, thank you for your help. –  Gar May 2 '12 at 17:04

$$E_{m}=\alpha_{m}x+y$$