Direct, Inverse and Joint Variation Help
emathlab.com › Algebra › FunctionsDirect, Inverse and Joint Variation Help. The relationship between two variables that vary directly is of the form y = kx . Note: x tripled, so y tripled. Note: k = y/x. When two variables vary directly, they appear to move in unison; i.e. if one doubles the other doubles, if one triples the other triples. The k factor is simply the relation, k ...