Function Notation for Dummies: No-Nonsense Explanation

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Hey there, math enthusiasts! Today, we’re diving into the fascinating world of Function Notation. If you’ve ever looked at a math problem and wondered what those funky \( f(x) \) symbols mean, you’re in the right place. In this beginner’s guide, we’ll demystify Function Notation, making it as clear as day. By the end of this article, you’ll be using Function Notation like a pro and solving math problems with ease.

What Is Function Notation?

First things first, let’s tackle the big question: What on earth is Function Notation? Well, it’s a way to represent mathematical relationships in a compact and efficient manner. Imagine you have a magical math wand that allows you to perform operations on numbers. That wand is Function Notation, and \( f(x) \) is its incantation.

The Basics of Function Notation

Now, let’s break down the mystery of \( f(x) \). In Function Notation, \( f \) represents the function, and \( x \) is the input variable. When you see \( f(x) \), it means you’re applying the function \( f \) to the value \( x \). Essentially, you’re saying, “Hey, the function \( f \), do your thing to \( x \).

For example, if we have \( f(x) = 2x \), it means that whatever number you put in for \( x \), the function \( f \) will double it. So, if you plug in \( 3 \) , you get \( f(3) = 2 \times 3 = 6 \).

Why Is Function Notation Used?

You might be wondering, “Why do we need this fancy \( f(x) \) stuff?” Great question! Function Notation is like a superhero in the math world. It makes complex mathematical expressions simpler and more manageable.

Imagine you’re dealing with a massive equation: \( y = 3x^2-5x + 7 \). That’s a handful, right? Now, rewrite it in Function Notation, and it becomes \( f(x) = 3x^2-5x + 7 \). Much cleaner and easier to work with, isn’t it?

A Practical Example

Let’s put Function Notation to work with a real-world example. Say you’re calculating the area of a square. In Function Notation, you can express it as \( A(side) = side^2 \). Now, when you want to find the area of a square with a side length of \( 4 \), you write \( A(4) = 4^2 = 16 \). Simple, right?

Function Notation vs. Traditional Notation

One of the superpowers of Function Notation is its clarity. Compare \( f(x) = 2x \) to \( y = 2x \). The former tells you immediately that \( f \) is a function, and it’s acting on \( x \). The latter could be interpreted in various ways. Is \( y \) a function of \( x \), or are they just related somehow? Function Notation leaves no room for ambiguity.

Common Misconceptions

As with any math concept, there are common misunderstandings about Function Notation. Let’s clear up a couple:

Misconception 1: \( f(x) \) is a Multiplication

Some think that \( f(x) \) means you’re multiplying \( f \) by \( x \). Nope, it’s not multiplication. \( f(x) \) represents a function acting on \( x \).

Misconception 2: You can only use \(f\)

While \( f \) is the most commonly used function symbol, you can use any letter or even a combination of letters to represent a function. For example, \( g(x) \) or \( h(t) \) are perfectly valid.

Exercises for Practice

Now that we’ve unravelled the basics of Function Notation, it’s time to flex those math muscles. Here are some exercises to reinforce your understanding:

Consider the relation $y=3x+2$, which is a function.
The $y$-values are determined from the $x$-values, so we say $y$ is a function of $x$, abbreviated to $y=f(x)$.
So, the rule $y=3x+2$ can also be written as follows.
$$ \large \begin{align} f: \mapsto \ &3x+2 \\
&\text{or} \\
f(x)= \ &3x+2 \\
&\text{or} \\
y= \ &3x+2 \end{align} $$
A function $f$ such that $x$ is converted into $3x+2$.

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Example 1

If $f(x)=4x-5$, find $f(2)$.

\( \begin{align} \displaystyle
f(2) &= 4 \times 2-5 \\
&= 3
\end{align} \)

Example 2

If $f(x)=x^2-5x+1$, find $f(-1)$.

\( \begin{align} \displaystyle
f(-1) &= (-1)^2-5(-1)+1 \\
&= 7
\end{align} \)

Example 3

If $f(x)=x^2-3x+2$, find $f(x+1)$.

\( \begin{align} \displaystyle
f(x+1) &= (x+1)^2-3(x+1)+2 \\
&= x^2+2x=1-3x-3+2 \\
&= x^2+x
\end{align} \)

Example 4

Given $f(x)=ax+b$, $f(1)=7$ and $f(2)=11$, find $a$ and $b$.

\( \begin{align} \displaystyle
f(1) &= 7 \\
a \times 1 +b &= 7 \\
a+b &= 7 \cdots (1) \\
f(2) &= 11 \\
a \times 2 + b &= 11 \\
2a+b &= 11 \cdots (2) \\
(2) &- (1) \\
(2a+b)-(a+b) &= 11-7 \\
a &= 4 \\
4 + b &= 7 \cdots (1) \\
b &= 3
\end{align} \)


Congratulations! You’ve embarked on your journey to master Function Notation. This beginner’s guide should equip you with the essential knowledge to tackle mathematical problems with confidence. Remember, Function Notation is your math superhero, simplifying complex expressions and making math more accessible. Keep practising those exercises, and soon you’ll be wielding the power of \( f(x) \) like a pro. Happy math-ing!


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