What is Function Notation?

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What is function notation? A function is in function notation when you use f(x) instead of y to indicate the outputs. You read f(x) as " f of x " or " f is a function of x "

Sometimes, the domain values (inputs) are related to the range values (outputs) with a rule. For example, take a look at the following situation.

Input	Function rule	Output
2	3 times input + 1	7
3	3 times input + 1	10

You can just use x to represent the inputs and y to represent the outputs and write y = 3 times x + 1.

y = 3x + 1

The notation y = 3x + 1 is one way to write this function. However, as already stated, there is another way. It is the function notation or f(x) = 3x + 1.

Note that f(x) does not mean " f times x "

Suppose that the value of x is 6. You can write f(6) and f(6) is read " f of 6 " or " f is a function of 6 "

f(6) represents the value of the function at x = 6.

For the example above, f(x) = 3x + 1 and f(6) = 3 × 6 + 1 = 18 + 1 = 19

Notice that A(s) = s × s is the function notation for the area of a square.

The different ways we can read A(s) are:

"A of s"

"A is a function of s"

"The area of a square is a function of the side"

Finally, notice from the table above, that the function notation P(x,y) = 2(x + y) has 2 variables. This is quite common when doing advanced math.