WeBWorK Problems

Simplifying Derivatives

Simplifying Derivatives

by Danny Glin -
Number of replies: 3
Looking at the following code (for example):


This gives a formula for $g of the form "2*3x^2".
Is there a way to get webwork to simplify this answer (i.e. multiply the two constants together)?
In reply to Danny Glin

Re: Simplifying Derivatives

by Davide Cervone -
The reduction rules are really very simple-minded, and are not a full Computer Algebra System. There is a lot more that could be done with them, but in their current form, the reduction you ask for is not available. Sorry!

In reply to Davide Cervone

Re: Simplifying Derivatives

by Dick Lane -
If I ask a student to differentiate a function and analyze that derivative function, I would like feedback (after closing date) about the first step to be close to a student's unsimplified result.  E.g., for
    $p  = Formula( "$a ($b x - $c) ($d x - $e)" ) ;
    $p1 = $p -> D(x) ;
I would be content if the student saw $p1 displayed as
    $a * $b ($d x - $c) + $a ($b x - $c) $d
involving just the Product Rule (and simpler stuff).

On the other hand, if I also asked for identification of critical point(s), then my Solution would include suitable algebra (with simplification of that derivative expression which keeps $a as a factor for other stuff).

I have had my calculus students use a CAS for many (20+) years and I often wish Webwork had a CAS.  The several Student packages in Maple (and rewrite rules in Derive & MuMath) show there is pedagogical value in selective inhibiting the power of a CAS.  I am not upset with MathObject symbolic reduction rules being simple-minded.
In reply to Dick Lane

Re: Simplifying Derivatives

by Paul Pearson -
Dear Dick,

You can require student answers to be factored:


Also, you should be able to use AnswerHints.pl to provide feedback comments to students who have a correct answer that is not fully factored:


Good luck!