In an algebraic expression or an equation, a letter other than the variable for which we can set the numerical value at will.
A parameter is one of the variable elements that figures in an algebraic expression or in a relation (equation, function, etc.) and for which we are interested in the characteristics that are connected to them.
Examples
- In the relation that defines a second-degree polynomial function of variable x : f(x) = a(b(x − h))² + k, the letters h and k are the parameters that characterize a horizontal translation and a vertical translation of the vertex of the graph, respectively. The letters a and b are also parameters that intervene in the appearance of the graph of the function.
- A family of parallel lines can be expressed by the equation y = mx + b. If m is constant, like for example in y = 2x + b, then this equation defines the set of parallel lines for which the slope is equal to 2. The parameter b represents the y-intercept of each line in this family.