On the exponential Diophantine equation $$(3pm^2-1)^x+(p(p-3)m^2+1)^y=(pm)^z$$ ( 3 p m 2 - 1 ) x + ( p ( p - 3 ) m 2 + 1 ) y = ( p m ) z

Abstract

Let m be a positive integer, and let p be a prime with \(p \equiv 1~(\mathrm{mod}~4).\) Then we show that the exponential Diophantine equation \((3pm^2-1)^x+(p(p-3)m^2+1)^y=(pm)^z\) has only the positive integer solution \((x, y, z)=(1, 1, 2)\) under some conditions. As a corollary, we derive that the exponential Diophantine equation \((15m^2-1)^x+(10m^2+1)^y=(5m)^z\) has only the positive integer solution \((x, y, z)=(1, 1, 2).\) The proof is based on elementary methods and Baker’s method.