How to prove $\frac{1}{1}+\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+...+\frac{1}{2^n}≥1+\frac{n}{2}$

Question

Okay, I definitely have to use induction I proved for the base case when $n=1$ and it was easy, but how do I prove when $n=k+1$?