posted by Holly .
When talking about a function f(x) is the f always the y point on a graph? I don't understand my book because it says f can be any letter. If f can be any letter and the question is f(6.9) and 6.9 is on the x and y axis then how do you know what to do?
On the y axis you put what you get when you apply the function to x. The letter f is just the name for the function, you can choose any letter of word for it; it doesn't have any meaning until you define it.
At x = 6.9, the y value is y = f(6.9).