For integers a, b and k, if a and b are positive and b = ak, then k ≥ 1

Question

Number theory: For integers $a, b$ and $k$, if $a$ and $b$ are positive and $b = ak$, then $k \ge 1$.

How would I proceed to answer this question? I was thinking of using contradiction but I don't know if it would lead me to the right answer?

Answer 1

If $k<1$, then $k\leq 0$ (because $k\in\mathbb Z$), so $ak\leq 0$ (because $a\geq 1$ and $k\leq 0$), which contradicts $b=ak>0$.

Answer 2

Here is a direct proof:

$a,b > 0 \implies k = \dfrac{b}{a} > 0 \implies k \ge 1$, since $k$ is an integer.