Evaluating functions from graphs is a fun and important skill you'll learn in Grade 9 Algebra I! Let's go through some simple steps to help you get really good at it!

1. Know the Function

First, figure out what kind of function you're looking at. Is it a straight line (linear), a curved shape (quadratic), or something else? Recognizing the shape helps you understand what it means!

2. Find the Input on the Graph

Next, look for the input value. This is often called the independent variable and is shown as $x$ on the horizontal axis. This is the starting point of your journey!

3. Get the Output Value

Once you locate $x$, draw a straight line up to the graph. Then, move to the side to see where it meets the vertical line. This spot shows you the output value, called the dependent variable $y$!

Example

If you want to find $f(3)$, start with $x=3$ on the graph. See where the line meets the graph. If it meets at $y=5$, then $f(3)=5$!

4. Look for Multiple Outputs

Keep in mind that some functions might not pass the vertical line test! This is important because it tells you if a function is really a function.

5. Practice, Practice, Practice!

The more you practice, the better you'll get at reading graphs. Try out different functions, and soon you'll be really good at evaluating like a pro!

Keep practicing, and you’ll get confident and accurate at evaluating functions from graphs! 📈✨