• Home
  • GCSE Topic Tests
  • GCSE Quick Maths Tests
  • Past Papers
  • Join our Newsletter
  • Blog

3 Minute Maths

GCSE maths walkthrough videos and worksheets

  • Maths and English Tutoring
  • Useful maths resources
  • THE ULTIMATE MATHS SURVIVAL GUIDE
  • Visit our Amazon store

GCSE advanced level – Equation of a line on a graph using y = mx + c

July 10, 2016 by Simon Leave a Comment

equations of lines2

Equation of a line

These questions tend to be fairly popular – and are usually presented either as a calculation, or by plotting on a graph yourself. You might also be asked to find some information by reading the graph, or calculate some additional coordinates.

To describe a straight line you only need to know two things –

  • How steep it is – the ‘gradient.’  There’s a couple of different ways to present this calculation and I’ve frequently seen something like y2 – y1 / x2 – x1. This is OK but it might be easier to remember ‘diff y / diff x.’
  • Where the line started from – the point where it crosses the y axis. This is usually called ‘c’ although some students write this as ‘b.’ There’s no difference 🙂

Whichever way, straight line graphs can be fairly useful and you’ll come across them in many applications such as converting temperature (centigrade to fahrenheit) or distance (miles to kilometres).

Top Tips!

  • They follow the general form ‘y = mx + c’
  • ‘m’ is the gradient and the easiest way to calculate is difference in y / difference in x
  • Gradients that look like a tick are positive
  • The other way is negative
  • ‘c’ means the point that the line crosses the y axis
  • If you don’t know ‘c’ use any set of co­ordinates to calculate
  • You’ll only usually need 3 or 4 points to draw a straight line, on an exam
  • The line goes on forever (might be useful to work out some answers)

If you’d like to ask for any more detail, or you’re not sure about anything, please do ask a question in the comments section.

All best with your studies



Watch on YouTube

Straight line graph passing through (1,5) and (2,7) – GCSE maths

Straight line graphs – equation passing through (3,5) and (7,13)

Line with gradient of 6 and passing through (5,10)

Line on a graph – GCSE maths advanced level

[easyazon_image align=”none” height=”160″ identifier=”1447987934″ locale=”UK” src=”https://www.3minutemaths.co.uk/wp-content/uploads/2016/06/51yMr2Q1AvL.SL160.jpg” tag=”matwra-21″ width=”113″]

[easyazon_image align=”none” height=”160″ identifier=”1910602132″ locale=”UK” src=”https://www.3minutemaths.co.uk/wp-content/uploads/2016/06/4128o11qTYL.SL160-1.jpg” tag=”matwra-21″ width=”108″]

[easyazon_image align=”none” height=”160″ identifier=”1844198049″ locale=”UK” src=”https://www.3minutemaths.co.uk/wp-content/uploads/2016/06/51D0Sa98XHL.SL160-1.jpg” tag=”matwra-21″ width=”113″]

Here’s some handwritten notes that might be useful:

straight line equation_1

straight line find equation_1

straight line graphs_1

 

 

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Anti spam - please answer to leave a comment. Thank you. * Time limit is exhausted. Please reload CAPTCHA.

Search for ANY GCSE maths topic

… or search by grade

A level blog Edexcel foundation Grade 1 Grade 2 Grade 3 Grade 4 Grade 5 grade 6 Grade 7 Grade 8/9 higher Indices maths resources Quick Tests Reasoning Surds

Copyright © 2025 · Magazine Pro Theme on Genesis Framework · WordPress · Log in

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish.Accept Read More
Privacy & Cookies Policy

Privacy Overview

This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary
Always Enabled
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Non-necessary
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.
SAVE & ACCEPT