Function Notation Here is a simple function, written in function notation: f(x) = 2x + 5              This notation tells you several things: The function is called  f The variable you will be replacing (by a number) is  x The function will take your number, double it, and add 5. Let's pick some numbers and find out what this function does to them. What will you get if you fill  6 in the function  f ? If you fill  6  in the function  f  you will get:        2 x 6 + 5 =  17 What will you get if you fill  10 in the function  f ? If you fill  10  in the function  f  you will get:     2 x 10 + 5 =  25 Here are the same two questions again, this time using function notation: If  f(x) = 2x + 5, find  f(6)        >>>        f(6) = 2(6) + 5 = 17 If  f(x) = 2x + 5, find  f(10)      >>>      f(10) = 2(10) + 5 = 25 Do you see how much simpler it is to write the question, and write your answer, when you use function notation? Here are a few more examples. We'll start with two new functions: g(x) = 4x               h(x) = - 3x Find  g(7).    (This means 'fill 7 into function g, and see what you get'). Your answer:           g(7) = 4 x 7 = 28 Find  h(11).    (This means 'fill 11 into function h, and see what you get'). Your answer:           h(11) = - 3 x 11 = - 33 If you think you understand function notation, try the  quiz. Functions Graphically | Back to Page One