Graphs
Writing a Function
Example 1
Write an exponential function 
for the graph below.
for the graph below. 
Step 1. Find the y-intercept
The y-intercept is identified on the graph as (0, 500).
Step 2. Substitute a point into the equation to find the common ratio
Step 3. Substitute the values of a and b into the equation.
y = 500 . 