Equation

A mathematical equation is a mathematical object containing two or more expressions connected by equals signs (=)."A statement of equality between two expressions. Equations are of two types, identities and conditional equations (or usually simply "equations")".  « Equation », in  Mathematics Dictionary, Glenn James et Robert C. James (éd.), Van Nostrand, 1968, 3 ed. 1st ed. 1948, p. 131.Une équation est une égalité entre deux expressions mathématiques, donc une formule de la forme A = B, où les deux membres A et B de l'équation sont des expressions où figurent une ou plusieurs variables, représentées par des lettres. ÉQUATION, mathématique - Encyclopædia Universalis The equals sign says that all of the expressions describe the same mathematical object.

An equation should not be confused with an expression. An expression is one piece of an equation, and does not have the equals sign. Equations are the most common type of formula.

There are two kinds of mathematical equations:
 The kind of equation that is either true or false; these are also called identities. For example: 

 The kind of equation that is only true for certain values of the variable(s). The equation is only true if the variable(s) have that value. For example:


The second kind is often used to solve problems in which finding the value of some variables is involved. For example, if
 , 

 Types of equations 
Equations can be classified by the types of operations and quantities involved. For example:
 An algebraic equation is an equation in which both sides are polynomials. These are further classified by degree:
 Linear equation for degree one
 Quadratic equation for degree two
 Cubic equation for degree three
 Quartic equation for degree four
 Quintic equation for degree five
 A Diophantine equation is an equation where the unknowns are required to be integers
 A differential equation is a functional equation involving derivatives of the unknown functions, which include:
 Ordinary differential equation
 Partial differential equation

 Related pages 
 Equation solving
 Formula
 Rate equation
 System of linear equations

References

Category:Equations