Short Answer 
To evaluate the function at the input value of 3, first identify this input on the graph’s x-axis. Then, draw a vertical line up to where it intersects the graph to find the corresponding output value on the y-axis, which represents f(3).
Step 1: Identify the Input
Start by clearly defining the input value for the function you are evaluating. In this case, the input is 3. This value represents the x-coordinate where you will find the corresponding output.
Step 2: Locate the Input on the Graph
Next, head to your graph and find the point on the x-axis that corresponds to the input value of 3. This step is crucial because it determines the exact location on the graph where you will check the output value.
Step 3: Determine the Output Value
Once you have located the input value on the x-axis, move vertically to determine where it intersects the graph. The output value can be found by looking at the y-coordinate at that intersection point. The value identified on the y-axis is the function’s value for f(3).