How is an equation best defined?

An equation is best defined as a mathematical statement that asserts the equality of two expressions. It typically consists of two sides separated by an equals sign (=), indicating that the values represented by the expressions on either side of the equals sign are the same under the given conditions. This concept is fundamental in mathematics because it enables the exploration of relationships between quantities and the solving of problems by finding unknown values.

In contrast, the other definitions provided do not encapsulate the essence of what an equation is. For example, a statement involving one expression being greater than another refers to an inequality rather than equality, which is not applicable to an equation. A formula used for solving problems can be related to various mathematical concepts but does not specifically define an equation. Lastly, a function describes a specific type of relationship between variables but not necessarily in terms of equality, as functions can represent many kinds of relationships beyond those captured by equations. Thus, the precise definition of an equation rests on its characterization as a statement of equality between two expressions.