Functions

By Lonnie Myers
Last updated over 6 years ago
4 Questions
Note from the author:
Introduction to Functions

A function works like a machine.  Numbers are put into the machine one at a time, and then the rule performs the operation(s) on each input to determine each output.  For example, when x = 3 is put into a machine with the rule y = 5x −7 , the rule multiplies the input, 3, by 5 and then subtracts 7 to get the output, which is 8.  This input and output can be written as an ordered pair: (3, 8).  Then it can be placed on an xy‑coordinate graph.
Find the output of the function machine at right when the input is x = 4 
y=

Using the function machine Find y when x = −1.  
y=

If the output of this relation is 45, what was the input?  That is, if y = 53, then what is  x
x=

Some relationships are special in that they are called functions. A relationship between the input values (usually x) and the output values (usually y) is called a function if for each input value, there is no more than one output value.

The set of all possible inputs of a relation is called the domain, while the set of all possible outputs of a relation is called the range. .
  • Item 1
  • Item
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  • Function
  • Not Function
In your Learning Log, describe what it means for a relationship to be a function.  How can you describe the differences between graphs of functions and graphs of non‑functions?  In your Learning Log, give examples of what a function and a non-function look like in a table and on a graph.  Title this entry “Functions and Non-Functions” and include today’s date.