Problem:
Suppose are rational numbers such that
Prove that .
Solution
Solution:
We have that , , and . By direct substitution we derive that satisfies the following polynomial equation of degree 216:
We observe that the polynomial can be rewritten as
for some integers . Hence by the Rational Root Theorem, if then it follows that . So . Similarly, as well.
But if , then we have , which is impossible. Hence only can occur. Thus .
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