# 1.8 Review and Summary

Access the following online video resources for additional instruction and practice with functions.

## Key Equations

 Constant function $f\left(x\right)=c$, where $\text{}c\text{}$ is a constant Identity function $f\left(x\right)=x$ Absolute value function $f\left(x\right)=|x|$ Quadratic function $f\left(x\right)={x}^{2}$ Cubic function $f\left(x\right)={x}^{3}$ Reciprocal function $f\left(x\right)=\frac{1}{x}$ Reciprocal squared function $f\left(x\right)=\frac{1}{{x}^{2}}$ Square root function $f\left(x\right)=\sqrt{x}$ Cube root function $f\left(x\right)=\sqrt[3]{x}$

## Key Terms

Dependent variable – an output variable

Domain – the set of all possible input values for a relation

Function – a relation in which each input value yields a unique output value

Horizontal Line Test – a method of testing whether a function is one-to-one by determining whether any horizontal line intersects the graph more than once

Independent Variable – an input variable

Input – each object or value in a domain that relates to another object or value by a relationship known as a function

One-to-One Function – a function for which each value of the output is associated with a unique input value

Output – each object or value in the range that is produced when an input value is entered into a function

Range – the set of output values that result from the input values in a relation

Relation – a set of ordered pairs

Vertical Line Test – a method of testing whether a graph represents a function by determining whether a vertical line intersects the graph no more than once