In mathematics, two variables are proportional if a change in one is always accompanied by a change in the other, and if the changes are always related by use of a constant.
A proportionality relationship happens when two quantities or numbers x and y are related multiplicatively by a fixed number. This can occur when either their ratio x/y is a fixed number (direct proportionality), or their product xy is a fixed number (inverse proportionality). If x is directly proportional to y, then we write . The fixed number of a proportionality relationship is called the constant of proportionality.
- ↑ "Compendium of Mathematical Symbols". Math Vault. 2020-03-01. Retrieved 2020-09-20.
- ↑ Weisstein, Eric W. "Proportional". mathworld.wolfram.com. Retrieved 2020-09-20.
- ↑ "Directly Proportional and Inversely Proportional". www.mathsisfun.com. Retrieved 2020-09-20.