Our method of proof involves finding the integral points on a genus 0 curve.
A general method for solving this type of problem is given in [3], [4]. We
parametrize the rational points on the curve then reduce the determination of
the integral solutions to a finite set of Thue equations. These can be solved
for example with the assistance of Magma [1]. In Section 2 we prove some
lemmas involving the integral solutions of certain quartic equations and then
prove our theorem in Section 3.