[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