The graph of function f is shown below. Find one value of x for which f(x) = 4 and find f(-2).
Answer: f (x) = 4 occurs when x = 0 and f (-2) = 2
We will use the concept of the downward parabola to find the solution.
The first thing we must do for this case is to observe the y coordinates for a given value of the x coordinate.
We have f (x) = 4. From the graph, it is clear this happens when x = 0.
On the other hand, we have f(-2). First, you can plot the value of x = -2 in the graph; then, you can draw a perpendicular line on the upward side and intersect to the parabola curve.
Now, you can see the point of (-2, 2) in the graph where f(-2) = 2. So, f(-2) is equal to 2.