Question 120384
First, you can pick values for x, solve the equation, and then graph the points. For example, the points 1, -1, 2, -2, 3, and -3. Put these numbers (one at a time) into x and solve the equation. Then, graph the points.

When you do this, you will get a graph that looks like a "v" that is shifted up two units.

As you probably recall, a way to prove that a graph is a function or not is by using the "vertical line test." 
In other words, if you were to put a pencil (or anything, basically) vertically (facing up and down) then the pencil should only touch the graph, at most, one time. If it touches the graph more than once, then it is NOT a function. But, if it touches the graph one time, then it IS A FUNCTION!

So what happens when you graphed the points? (Make sure that you connected the dots!) It looks like a "v" right? Now, did you put on pencil on it vertically to test if the "v" touched it more than once?

After you do this, the answer will be clear.

This graph, is in fact, a function!