# polyroot() is an inert function of polymonial root holder, 
 poly(a,b,c,d,f,x) is holder of polymonial coefficient for a+b*x+c*x^2+d*x^3+f*x^4,
polyroot(a,b,x) is holder of polymonial root of a and b, where a and b are roots of polymonial,
it can be activated by activate();


polyroot(a_,b_) := x^2-a*x-b*x+a*b;
polyroot(a_,b_,c_) := expand((x-a)*(x-b)*(x-c));
polyroot(a_,b_,c_,d_) := expand((x-a)*(x-b)*(x-c)*(x-d));

polyroot(a_ and b_) := x^2-a*x-b*x+a*b;
polyroot(a_ and b_,c_) := expand((x-a)*(x-b)*(x-c));
polyroot(a_ and b_ and c_) := expand((x-a)*(x-b)*(x-c));
polyroot(a_ and b_ and c_,d_) := expand((x-a)*(x-b)*(x-c)*(x-d));
polyroot(a_ and b_ and c_ and d_) := expand((x-a)*(x-b)*(x-c)*(x-d));