Variable (mathematics)

A symbol representing a quantity that can take different values in a mathematical expression or problem. Its role depends on context: it may be unknown, freely chosen, or changing.

Unknown: A value in a problem that is not yet known and must be determined. An equation-solving variable often stands for the value being sought.
Algebraic expression: A combination of numbers, variables, and operations that represents a mathematical quantity. Variables combine with operations to form expressions whose values depend on assignments.
Linear equation: An equation in which each variable has degree at most one. Solving a linear equation finds values of variables that satisfy a simple constraint.
Random variable: A function that maps outcomes of a random experiment to numerical values. Unlike a generic variable, it has a precise probabilistic definition over outcomes.
Constant (mathematics): A quantity or symbol whose value is fixed within a specified mathematical context. A constant remains fixed where a variable may take different values.
Equation: A mathematical statement asserting that two expressions have equal value. An equation restricts variable values to those that make both sides equal.
Coordinate system: A system that identifies points using ordered numbers relative to chosen axes or references. Coordinate variables encode a point's position in space.
Dummy variable: A variable used temporarily as a placeholder, often in sums or integrals, without affecting the result when renamed consistently. Its name is interchangeable because its role is local and bound.
Parameter: A quantity held fixed within a problem or model but allowed to vary across different cases. Parameters shape a family of expressions while variables range within each case.
Function (mathematics): A rule that assigns each input in a domain exactly one output. Function notation distinguishes input variables from output values.

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