hmm, better if you choosed wisely so that the origin becomes the center
let A be the point (4n,0) and B be the point (n,0) for some positive real n.
let P(x,y) satisfies:
|PA| = 2|PB|
|PA|^2 = 4|PB|^2
(x-4n)^2 + y^2 = 4[(x-n)^2 + y^2]
x^2 -8nx + 16n^2 + y^2 = 4x^2 - 8nx + 4n^2...