Function Notation                  Page 2 of 4

Functions as Equations

An equation can also be a function. Remember, a function takes an input value and assigns it an output value.  If a function is written as an equation, the equation tells you exactly what the function is going to do with the input value to get the output value.

For example, the equation y = 3x is a function.  You plug your input value in for x and it gets multiplied by 3.  If your input value was 5, the output would be 3(5) = 15.  If the input value was 7, the output would be 3(7) = 21.

When a function is written as an equation, the equation tells you the relationship between the input and output values.  The function y = x - 1 takes input values and subtracts 1 to give the output values.  The function y = x/2  takes input values and divides them by 2 to give the output values.  

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