Hey there! Before we start with the problem, you mean f(2) instead of F(2) if I'm correct. In maths, variables are case-sentitive so F and f both are different.
First, f(2) means the value of y at x = 2.
f(2) is when we substitute x = 2 in and receive the output (y-value).
In coordinate plane, we have (x,y) as a point. What we have to do is to look at the graph, you will see the point that contains (2,-8)
That's it! Refer above, f(2) is when we substitute x = 2 and get y-value.
Hence, f(2) = -8
Let me know if you have any questions!
Topic: Function