An equation that is true no matter what values are chosen. In mathematics an identity is an equality relating one mathematical expression A to another mathematical expression B such that A and B which might contain some variables produce the same value for all values of the variables within a certain range of validity. An equality in mathematical sense is only true under more particular conditions.
X y 2 x 2 2 xy y 2.
For example if a is any non-zero number then multiplying a by 1 gives the product as the number itself. X y 2 x 2 2 xy y 2. In other words A B is an identity if A and B define the same functions and an identity is an equality between functions that are differently defined. In mathematics an identity is an equality relating one mathematical expression A to another mathematical expression B such that A and B which might contain some variables produce the same value for all values of the variables within a certain range of validity.