Loading please wait

The smart way to improve grades

Comprehensive & curriculum aligned

Try an activity or get started for free

Use Inverse Functions

In this worksheet, students find the inverse of functions using the method of finding an alternative subject.

'Use Inverse Functions' worksheet

Key stage:  KS 4

Year:  GCSE

GCSE Subjects:   Maths

GCSE Boards:   Pearson Edexcel, OCR, Eduqas, AQA,

Curriculum topic:   Algebra

Curriculum subtopic:   Notation, Vocabulary and Manipulation Language of Functions

Difficulty level:  

Worksheet Overview

An inverse function reverses a previous function.

So if f(x) is a function, we write its inverse as f-1(x).


There are three steps to follow when finding an inverse function:

Step 1: Change f(x) = into y =.

Step 2: Swap x and y.

Step 3: Make y the subject.



Let's have a look at an example now.


e.g. Find the inverse of f(x) = 3x + 4.


Step 1: y = 3x + 4

Step 2: x = 3y + 4

Step 3: x - 4 = 3y

(x - 4) ÷ 3 = y


So f-1(x) = (x - 4) ÷ 3




In this activity, we will find the inverse of functions using the method shown above of finding an alternative subject of the function. 

What is EdPlace?

We're your National Curriculum aligned online education content provider helping each child succeed in English, maths and science from year 1 to GCSE. With an EdPlace account you’ll be able to track and measure progress, helping each child achieve their best. We build confidence and attainment by personalising each child’s learning at a level that suits them.

Get started

Try an activity or get started for free