The function $f:\mathbb{R} \to \mathbb{R}$ is such that $f(f(x+1)) = x^3+1$ for all real numbers $x$. Prove that the equation $f(x) = 0 $ has exactly one real root.
Problem
Source: Bulgaria EGMO TST 2020 Day 2 Problem 2
Tags: function, algebra, functional equation, injectivity, bijection, surjectivity