https://www.onlinemathlearning.com/rational-root-theorem.html
A rational zero/root is a rational number, which is a number that can be written as a fraction of two integers
http://algebra-review.yolasite.com/theorems-about-roots.php
https://www.onlinemathlearning.com/dividing-polynomials-synthetic-division.html
linear factor – cannot be factored further