# Function Notation Formula

Functions or Functional Notations are referred by the letter ‘f’ and written as f(x), sometimes in the form of g(x), h(a) etc.

### Solved Examples

Question 1: Represent y =

$$\begin{array}{l}x^{2}\end{array}$$
+ 4x + 1 using function notation and find the value of y at x = 3.

Solution:

Given function is,
y =
$$\begin{array}{l}x^{2}\end{array}$$
+ 4x + 1
By using function notation,
f(x) =
$$\begin{array}{l}x^{2}\end{array}$$
+ 4x + 1
Value of y at x = 3 means f(3).
So, f(3) =
$$\begin{array}{l}3^{2}\end{array}$$
+ 4
$$\begin{array}{l}\times\end{array}$$
3 + 1 = 9 + 12 + 1 = 22

Question 2: Represent the given function y =

$$\begin{array}{l}x^{3}\end{array}$$
– 4x using function notation and find the value of y at x = 2.

Solution:

Given function is,
y =
$$\begin{array}{l}x^{3}\end{array}$$
– 4x
By using function notation,
f(x) =
$$\begin{array}{l}x^{3}\end{array}$$
– 4x
The value of y at x = 2 means f(2).
Therefore, f(2) =
$$\begin{array}{l}2^{3}\end{array}$$
– 4
$$\begin{array}{l}\times\end{array}$$
2 = 8 -8 = 0