This math topic revolves around finding the domain of functions where the function's structure involves a linear fraction over the square root of a quadratic expression. Each problem presents a different function and asks to identify its domain represented on a number line. The primary skill focused here is handling expressions within square roots to determine the set of real numbers (x-values) that make the function’s denominator non-zero and the radicand non-negative. These problems help to reinforce understanding of function domains, particularly when working with square roots and quadratic expressions.