newb algebra question



maxima-bounces at math.utexas.edu wrote on 12/18/2007 08:49:25 AM:

> I have this:
>                                            2
>                                   sqrt(2) s
> (%o52)                  -------------------------------
>                                  2                    2
>                         sqrt(2) w  + 2 s w + sqrt(2) s
> 
> I want to divide num and den by sqrt(2), resulting in:
> 
>                                      2
>                                    s
> (%o52)                  -------------------------
>                          2                    2
>                         w  + sqrt(2) s w +  s
> 
> What's the easiest way to do this?

Things like this aren't always so easy to do. Here is an obscure way:

  (%i37) algebraic : true$
  (%i38) sqrt(2) * s^2 /(sqrt(2) * w^2 + 2 * s * w + sqrt(2) * s^2)$
  (%i39) 1/ratsimp(1/%);
  (%o39) s^2/(w^2+sqrt(2)*s*w+s^2)

You can also try something like

  (%i17) algebraic : true$
  (%i18) sqrt(2) * s^2 /(sqrt(2) * w^2 + 2 * s * w + sqrt(2) * s^2)$
  (%i19) (num(%) / sqrt(2)) / ratsimp((denom(%) / sqrt(2)));
  (%o19) s^2/(w^2+sqrt(2)*s*w+s^2)

As you gain experience in using a CAS, you might find that you don't
care as much about the presentation of an expression. Yes, all that
changes when you want to publish your work -- we like things to be
just right.

Barton