
equation


A mathematical statement that represents the equality of two expressions involving either constants, variable(s), or both. For example, 1 + 2 = 3 is an equation. So is xy =1.
If an equation is true for all possible value(s) of the variable(s), it is called an identity and denoted by . For example, (a+b)(ab) a^{2}  b^{2} is an identity.

