Consider the system of two equations
x+y=2
x*y=4
Let's try to solve this using Maple's solve command.
This seems at first glance like one solution, but actually it is two, which I see if I use evalf.
Solving the equations by hand I get two solutions
y=1+sqrt(3)*i, x=4/y
y=1-sqrt(3)*i, x=4/y
If I use evalf on these two solutions I get the same result as the two solutions using solve.
My question is where does the expression y=2* RootOf(_Z^2-_Z+1) come from?
By hand, y seems to be the solution to y^2-2y+4=0.