Graphs

Writing a Function

Example 3

Write an exponential function WritingFunctionFromGraph for a graph that includes (2, 4) and (3, 16).

Step 1. Since the two points have an x-increment of 1, the ratio between their y-values is the common ratio. Use this to find the value of b.

FuncGraphEx3-1

Step 2. Substitute either point into WritingFunctionFromGraph, solve for "a."

Using (2,4) FuncGraphEx3-2

Using (3,16) FuncGraphEx3-3

Step 3. Substitute "a" and "b" into the original function WritingFunctionFromGraph.