A-Math: How Do You Sketch A Modulus Graph?

Last Sunday while coaching my A-Math students on a question on Modulus Functions, we did solving of Modulus equation which is of no big problem as long as you get the basic concept correct.

|x| = x when x >= (more than and equal to) 0 or |x| = -x when x < 0

When we came to the next part of the question which involves Sketching of Modulus Graph, that's where the interesting happens.

Read about the Differences between Drawing and Sketching in this post.

When question involves sketching of graph, we usually do not need
- a table of values
- axis which are evenly marked out.

Sketching of Graph should however includes
- critical points (i.e x - intercept(s), y-intercept, turning point (if you are sketching a quadratic graph))

Let's take a look at the working of 2 different students:

Student A:

  • Sketch the modulus graph using table of values
  • Join up the points in a straight line manner

Student B:

  • Sketch the modulus graph using a series of 2 other graphs

Note the difference in the shape of the 2 graphs.

I certainly hope that my student A is convinced that using a table of values is not recommended for drawing modulus graphs. Moreover, many questions involving modulus could be that of Trigonometry graphs! So be like student B, draw modulus graph using a transformation of a series of graphs

Related Post

Linear Law,Just 1 Strategy Makes A Grade Difference What is Linear Law? It is a tool which will allow you to transform non-straight line equation to straight line equation so that you can plot a stra...
A-Math: How to Sketch Modulus Graph This morning, I received an email from a student on asking how to draw a modulus graph with and without boundary condition. What is boundary co...
What Is The Difference Between Sketch And Draw? It is important to know the difference between Sketch A Graph & Draw A Graph. Sketch ==> On foolscap paper Best Representation of the ...
A-Maths: Application Question on Modulus Graph Based on my observations on recent mid-year exams papers, prelims papers, it seems like many schools are setting highly application questions for many...
E-Maths: General Equation and Graphs of Line Line is part of us, in almost everything you see. You must understand what equation of line is, how to find gradient, how to find the x and...

Hi, I'm Ai Ling Ong. I enjoy coaching students who have challenges with understanding and scoring in 'O' Level A-Maths and E-Maths. I develop Math strategies, sometimes ridiculous ideas to help students in understanding abstract concepts the fast and memorable way. I write this blog to share with you the stuff I teach in my class, the common mistakes my students made, the 'way' to think, analyze... If you have found this blog post useful, please share it with your friends. I will really appreciate it! :)

5 Responses to A-Math: How Do You Sketch A Modulus Graph?

  1. In my opinion, student A diagram was wrong because he or she does not use equal scale for both x and y -axis. Thus, it has created the weird shape different from standard curve shape. However, I will agree with you in encouraging students to follow Student B's method for curve sketching.


Leave a reply