Affine transformations

[kosta_m]

Can anybody tell me where I can find
the proof that any ellipse remains ellipse
after any affine transformation.
Thanks!

[V-man]

You can scale a ellipse to make a circle so ....

Then again a circle is an ellipse with the 2 focal points being = .

Besides that, what can I say. A transformation will be applied to the equation, so why don't you just proove it that way, for each case (translation, rotation, .....)

V-man