What describes a direct variation between two variables?

A direct variation between two variables occurs when one variable is a constant multiple of the other, establishing a proportional relationship. This means that as one variable increases or decreases, the second variable changes at a consistent rate. The relationship can be expressed mathematically as ( y = kx ), where ( k ) is the constant of proportionality, indicating that for any value of ( x ), the value of ( y ) is directly influenced by it.

In contrast, other options describe different types of relationships. A random relationship lacks a consistent formula, meaning there is no predictable pattern. A relationship defined only at specific points cannot be characterized as a direct variation since it suggests that the variables do not maintain a consistent ratio throughout their domains. Finally, simultaneous equations can involve direct variations among other types of relationships, but they encompass a broader category of relationships that do not exclusively describe direct variation.

Thus, the first option correctly captures the essence of direct variation as it pertains to a consistent, proportional relationship.