Graphs

Writing a Function

Example 2

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

Step 1. Substitute the values of each point into the function WritingFunctionFromGraph.

1.) 2 = a.b2 2.) 4 = a.b3

Step 2. Solve for "a" using the first function

FuncGraphEx2-1

Step 3. Substitute the value of "a" from step 2 into the second function. And solve for "b".

FuncGraphEx2-2

Step 4. Substitute "b" back into the first function and solve for "a" .

FuncGraphEx2-3

Step 5. Substitute the values of "a" and "b" into the original function WritingFunctionFromGraph.
y = FuncGraphEx2-4. 2 x