# Math Help - calling an equation..

1. ## calling an equation..

suppose i have this command..

$$blahbah$$

If blah, then heh..

$$blahbahblah$$

the two equations will be labeled then.. my problem is, how would i call the equation if i am going to use it somewhere..

for example, "using equation ?, we get..."

i can do it manually, but suppose i have lots of equations? generally, one wouldn't and not advisable to count for the equation label,,

got my problem?

2. Hello, kalagota

Use \label{} and \ref{} :

Code:
$$x=y \label{name-of-this-equation}$$

From equation \ref{name-of-this-equation} we have...
\ref{name-of-this-equation} prints the number of the equation labelled "name-of-this-equation". In case you don't know it : you must compile twice your document when you use \label{} and \ref{}.

Another possibility is to use the command \eqref{} (from the package amsmath) instead of \ref{}. \eqref{} puts labels of equations between parenthesis, \ref{} doesn't.

3. thanks bro!