I need help to prove this.
Let $f:\mathbb{R}\longrightarrow{\mathbb{R}}$ be an absolutely continuous function in any interval of the form $\left. [ -k,k \right ]$. If $f^{\prime}$ is in $L(\mathbb{R})$ and $\left\{{x_n}\right\}$ is a sequence that converges to infinity. Show that $\displaystyle\lim_{n \to{\infty}}{\displaystyle \left |{f(1+x_n)-f(x_n)}\right |}=0$
Thanks.