[no subject]

• To: mathgroup at yoda.physics.unc.edu
• From: sergio at shark.inst.bnl.gov (Sergio Rescia)
• Date: Tue, 28 Sep 93 15:20:47 EDT
• Sender: Sergio.Rescia.Phone:516-282-4232.FAX:516-282-5773 at shark.inst.bnl.gov

```I am trying to use Eliminate to eliminate the unknown y in a system of 2 equations:

In[1]:= Eliminate[{ (x-a)^2+(y-b)^2==r^2 ,
x^2+y^2==9 },            {y}]

4    2           2      2
Out[1]= r  + r  (-18 - 2 a  - 2 b  + 4 a x) ==

2    4       2      2  2    4               3          2
>    -81 - 18 a  - a  + 18 b  - 2 a  b  - b  + 36 a x + 4 a  x + 4 a b  x -

2  2      2  2
>     4 a  x  - 4 b  x

Is there any way to force Eliminate to produce a result in the form:

expr==0

Or better yet there is any smart way to compute directly the discriminant of the second degree equation
(in x) Out[1]?

Thank you.

Sergio rescia

```

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