This math topic focuses on determining the domain of functions containing quadratic expressions under a square root, specifically those that potentially have complex roots due to negative discriminants. The problems require identifying the correct number line representation that depicts the domain of various quadratic root functions. The exercises belong to an introductory level of understanding domains and ranges, particularly emphasizing how the presence of complex roots affects the domain of square root functions. The goal is to help students visualize and interpret these concepts on number lines.