Ways to

**Tell if Something Is a Function**.**Functions**are relations that derive one output for each input, or one y-value for any x-value inserted into the equation. For example, the equations y = x + 3 and y = x^{2}- 1 are**functions**because every x-value produces a different y-value.When the function is defined?

In mathematics, an expression is called well-

**defined**or unambiguous if its**definition**assigns it a unique interpretation or value. For example, if f(x) = 1/x, then f(0) is undefined, but this has nothing to do with the question of whether f(x) = 1/x is well-**defined**. It is; 0 is simply not in the domain of the**function**.What are the rules of a function?

Output variable = Dependent variable = Range.

**Functions**are usually represented by a**function rule**where you express the dependent variable, y, in terms of the independent variable, x. y = 2.50 ⋅ x. You can represent your**function**by making it into a graph.