Explain the difference between f and f (x).

F is a function. It takes inputs and then produces an output. The notation f (x) is saying more specifically that the function is taking an input x and producing the output f (x). For example, if you look at f (x) = x2, you can think that f is the "squaring function", with input x and outputs x2. You can think that "f" is like the name of the function. f1 (x) = x2 f2 (x) = 6x + 3 Above, you know which function I'm talking about if I say f2. But often, people will just call it as the function f2 (x)