How do you evaluate functions?
The same way that you substitute values into equations!
Example 1What is the value of $$ x $$ given the equation $$ y = 2x $$ when $$ x = 5 $$?
Substitute '5' in for x :
The one new aspect of function notation is the emphasis on input and output .
![example of how to evaluate a function in math](images2/evaluating-functions/example-of-evaluating-a-function-in-math.png)
What is the value of $$ x $$ given the equation $$ y = x-5 $$ when $$ x = 7 $$?
Again, this new way involves an input and output .
![example 2 of how to evaluate a function](images2/evaluating-functions/example-2-of-evaluating-a-function-in-math.png)