Question 22
Prove that there are no positive integers $x$, $y$, $z$ such that
$$
(3x + 4y)(4x + 5y) = 7^{z}
$$
$$
(3x + 4y)(4x + 5y) = 7^{z}
$$
MathNet 2019-part-06 — 184 problems (EN–VI) Question 22
Math Olympiad Vault · MathNet 2019-part-06 — 184 problems (EN–VI)