First I'll approach it graphically to see what
to expect; then I'll do it algebraically
The graph of is this parabola:
The graph of is this ellipse:
Put them together on one graph:
The graph of is this ellipse:
Since these graphs cross in two points, these will be two
real solutions, and since parabolas and circles could cross
as many as 4 times, there will two imaginary solutions as well
The first equation is already solved for , so we substitute
for in the second equation:
That does not factor, so we solve that for
using the quadratic formula:
where , ,
So we have two solutions for
and
If we substitute the first value of in , we get
If we substitute the second value of in , we get
The first value of gives these two solutions for x:
and
The second value of gives these two solutions for x:
, ,
but since is a negative number, it's going to be
imaginary, so we factor out of it, ,
so we have
and of course
So we have four solutions for (,)
(, ) = (, )
(, ) = (, )
These are the points where the curves above cross, and are the two
real solutions.
Here are the two imaginary solutions:
(, )
(, )
Edwin