Are there any software to computer resultant for a system of equations (more than 2) with more than 2 variables? 



any software to compute multivariable resultant?
Maple will do it.


<http://www.maplesoft.com/support/help/AddOns/view.aspx?path=Algebraic/Resultant>


You can also do it in C, or Matlab with MARS:


<http://gamma.cs.unc.edu/MARS/>


