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Relations and Functions
Vocabulary
Fill in the definitions.
Word  Definition 
Relation  _______________________________________________________ 
Function  _______________________________________________________ 
In your own words, describe the difference between a relation and a function.
What are the requirements for a relation to be a function?
Practice
Determine if each relation is a function and explain why:
Representation  Example 
Is it a function? Why? 

Set of ordered pairs  (1,3), (2,4), (3,3), (4,19) (a subset of the ordered pairs for this function)  
Equation 
\begin{align*}y=7x4\end{align*} 

Graph 

Answer the following questions:
 Can a function definition be written in the form \begin{align*}x = 3y\end{align*}
x=3y instead of \begin{align*}y = 3x\end{align*}y=3x ?  Is it mandatory for a function to have both an input and an output?
 Give an example of a relation that is not a function, and explain why it is not a function.
Determine if each relation is a function:
1) \begin{align*}(1,7) (0, 2) (0, 4) (1, 8) (2, 13)\end{align*}
2) \begin{align*}x = y\end{align*}
3)
4)
5)
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