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Does the equation $x^e+e^x=e^n$ have any real solutions?

数论 Math StackExchange -2 票 1 回答 68 浏览 提问者: daryoosh hadizade 2026-08-18 22:55
number-theory exponential-diophantine-equations

问题内容

Let $x,n$ be positive integers. Consider the equation $$e^x+x^e=e^n$$ I would like to know whether this equation can have any positive integer solutions. Since $x^e \gt 0$, any solution must have $n \gt x$. Dividing by $e^x$, $$1+\left(\frac{x}{e}\right)^e=e^{n-x},$$ so $$n-x= \log\bigg(1+\frac{x}{e}\bigg)^e \\n-x = e \log\bigg(1+\frac{x}{e}\bigg) \\ n-x = \bigg(1+\frac{x}{e}\bigg)$$

回答 (1)

bjcolby15 0 票 2026-08-18 23:28 原文

Hint: If $e$ is the transcendental number $2.718281828...$ and you carried out your equation to its natural conclusion (i.e. solved the equation for $x$), what would you be able to conclude for $n \gt 1$?