# [LON-CAPA-dev] formularesponse with maxima: Addition issues?

**Stefan Bisitz
**
lon-capa-dev@mail.lon-capa.org

*Wed, 20 Jun 2007 13:08:45 +0200*

Hi,
Before starting a new bugreport, I'd like to ask if someone knows any
issues with formularesponse with maxima using addition?!?
It seems that LON-CAPA/Maxima doesn't accept an answer which contains
additions. For example, use the "Formula Response using Computer Algebra
System" template and add "+5" or "+x" to $derivative:
--------
<problem>
<script type="loncapa/perl">
$k=&random(3,6,1);
$formula="a*x^$k";
$m=$k-1;
$derivative="$k*a*x^$m+x"; # original: $derivative="$k*a*x^$m";
</script>
<startouttext />
What is the derivative of <tt>$formula</tt> with respect to x?
<endouttext />
<formularesponse answer="$derivative">
<textline size="25" />
</formularesponse>
</problem>
--------
>*From now on, LON-CAPA displays "ERROR:Computer's answer is incorrect".
*
Using mathresponse or formularesponse WITH sampling points, no problems
could be seen.
Any idea what's wrong?
Stefan Bisitz