Assume $f(x)$ is differentiable at $e$. Prove that if $f\,'(x)\gt 0$, then $f(e-k)\lt f(e)\lt f(e+k)$ for all positive $k$ sufficiently small.

Problem: 

Assume $f(x)$ is differentiable at $e$. Prove that if $f\,'(x)\gt 0$, then $f(e-k)\lt f(e)\lt f(e+k)$ for all positive $k$ below some sufficiently small value.

Answer: 

It is true that if $f\,'(x)\gt 0$, then $f(e-k)\lt f(e)\lt f(e+k)$ for all positive $k$ below some sufficiently small value.