Which of the following best describes constants in an expression?

The best description of constants in an expression is that they are fixed values that do not change. Constants are numerical values, such as 3, -7, or 5.2, that are incorporated into mathematical expressions to provide specific information without any variability. Unlike variables, which can represent different values depending on the situation, constants remain the same throughout calculations, providing stability and a reference point in equations.

This definition emphasizes the role of constants in mathematical expressions, showing that while they contribute to the formations of those expressions, they do not alter or adapt based on other conditions or variable inputs. This understanding is crucial when working with algebraic equations, as constants often form the base on which variable relationships are established.