f(a) means the value of f(x) is ... when x = a. That means if we substitute x = 3, we would get f(3).
f(3) also means the value of f(x) is ... when x = 3.
f(x) can also be defined as y // f(x) = y
Find f(3) by graph.
You can find the value of f(x) at specific domain from the graph by looking at x = 3 then look up to where the point or where the graph passes. From the graph, when x = 3 as we look up and the graph passes y-coordinate at 1.
