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## Re: [Axiom-developer] Am I posing this solve problem wrong?

 From: Bill Page Subject: Re: [Axiom-developer] Am I posing this solve problem wrong? Date: Sun, 4 May 2008 21:49:20 -0400

```On Sun, May 4, 2008 at 7:32 PM, C Y  wrote:
> I'm trying to solve for y.  In Axiom:
>
> (1) -> E1 := x^2*D1^2+(y-y1)^2*C1^2 - C1^2*D1^2
> (1) ->
>          2  2      2         2 2     2 2     2  2
>   (1)  C1 y1  - 2C1 y y1 + C1 y  + D1 x  - C1 D1
>                                                     Type: Polynomial
> Integer
> (2) -> solve(E1=0,y)
> (2) ->
>           2  2      2         2 2     2 2     2  2
>   (2)  [C1 y1  - 2C1 y y1 + C1 y  + D1 x  - C1 D1 = 0]
>                              Type: List Equation Fraction Polynomial
> Integer
>
> Am I doing something wrong?

I guess you need to be a little more explicit about the variables:

(1) -> E1:MPOLY([x,y],EXPR INT) := x^2*D1^2+(y-y1)^2*C1^2 - C1^2*D1^2

2 2     2 2      2         2  2     2  2
(1)  D1 x  + C1 y  - 2C1 y1 y + C1 y1  - C1 D1
Type: MultivariatePolynomial([x,y],Expression Integer)
(2) -> solve(E1=0,y)

+----------+                 +----------+
|   2     2                  |   2     2
D1\|- x  + C1   + C1 y1    - D1\|- x  + C1   + C1 y1
(2)  [y= -----------------------,y= -------------------------]
C1                          C1
Type: List Equation Expression Integer
(3) ->

Regards,
Bill Page.

```