Using the rational root theorem, it is found that your friend is correct.
<h3>What is the rational root theorem?</h3>
It is a theorem that states that for a polynomial with integer coefficients, with q being the factors of the leading coefficient and p being the factors of the constant, every <u>possible rational root</u> is the format .
In this problem:
The leading coefficient is 1, hence it's only factor is , thus guaranteeing that every possible rational zero is an integer, which means that your friend is correct.