🚀 go-pugleaf

Michael De Nil wrote:

> Heyz
> 
> someone who knows how to add a newline after a math-expression ?
> currently, I always \end{displaymath} and \begin{displaymath} to add a
> newline...
> 
> anyone plz ?
> michael

If I'm going to have multiple lines of math, I use the eqnarray or 
eqnarray* environments.  (The * version doesn't number the lines.  The 
unstarred version numbers all lines that don't have the \nonumber command 
in them.)  It's automatically formatted as three columns, assuming the 
relation (=, <, >, etc.) is the second column.  Columns are separated by &, 
and newlines are made with \\.  Here's an example of the derivation of the 
quadratic equation:

Given \[Ax^2+Bx+C=0\] what is $x$?

We begin by defining $b=\frac{B}{A}$ and $c=\frac{C}{A}$.  This allows
us to rewrite the expression as
\[
x^2 + bx+c = 0
\]

Now, we remember that $\left(p+q\right)^2=p^2+2pq+q^2$, and apply this
to the expression.
\begin{eqnarray}
x^2 + bx + \frac{b^2}{4} -\frac{b^2}{4} +c &=&0\nonumber\\
\left(x+\frac{b}{2}\right)^2 &=& \frac{b^2}{4} - c\nonumber\\
x+\frac{b}{2} &=& \pm \sqrt{\frac{b^2}{4}-c}\nonumber\\
x &=& -\frac{b}{2} \pm \sqrt{\frac{b^2}{4}-c}\nonumber\\
x &=& \frac{B}{2A} \pm
\sqrt{\frac{B^2}{4A^2}-\frac{C}{A}}\nonumber\\
x &=& \frac{-B\pm\sqrt{B^2-4AC}}{2A}
\end{eqnarray}

(This is the one I posted on http://planetmath.org a few months ago.)

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