MYTUTOR SUBJECT ANSWERS

313 views

Core 3 - Modulus: Solve the equation |x-2|=|x+6|.

Modulus, also known as absolute value, takes whatever's between the |straight brackets| and makes it positive. For example, |3|=3, and |-3|=3. Interestingly, if you have any real number x, then |x|=sqrt(x2). Try putting some numbers in and see!

We can't solve a modulus question until we get rid of the straight brackets, but this little trick will do the job every time. If we square both sides of the modulus equation in the last paragraph, we get |x|2=x2. So modulus brackets disappear when we square both sides of our equation. Let's try it...

|x-2|2=|x+6|2

(x-2)2=(x+6)2

x2-4x+4=x2+12x+36

-16x=32

x=-2

This trick is great, because the xterms cancel out and there's no quadratic equation to mess about with. Beware though, this will not be the case in all questions - if you get a quadratic equation to solve, you may end up with more than one solution. Try these bonus questions and see for yourself:

(1) Solve the equation |x+4|=|x-5|.​

(2) Solve the equation |x-3|=|2x|.​

(3) Solve the equation |3x-1|=|3-x|.​

Michael F. A Level Maths tutor, 11 Plus Maths tutor, 13 plus  Maths t...

6 months ago

Answered by Michael, an A Level Maths tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

295 SUBJECT SPECIALISTS

£22 /hr

Laura P.

Degree: Mathematics (Masters) - Lancaster University

Subjects offered:Maths

Maths

“Hi! I'm Laura, a Maths student at Lancaster. I have such a passion for Maths that I hope my tutorials will be both engaging and interactive, so all can enjoy!”

£20 /hr

George P.

Degree: Mathematics (Bachelors) - Exeter University

Subjects offered:Maths

Maths

“Hey! I'm George and I'm in my second year studying Maths at Exeter. I regularly teach first year students and would love the opportunity to teach even more!”

MyTutor guarantee

£22 /hr

Jonathan P.

Degree: Physics (Masters) - Durham University

Subjects offered:Maths, Physics

Maths
Physics

“About Me: I am a Physics student at Durham University. My passion is physics, and by association maths, I will aim to instil asimilar passion in students during my tutorials. I am a highly patient and approachable individual.  I have...”

About the author

Michael F.

Currently unavailable: for new students

Degree: Mathematics (Bachelors) - Oxford, Pembroke College University

Subjects offered:Maths, Further Mathematics

Maths
Further Mathematics

“Personal Description: I am about to start my first year of studying Maths at Oxford University. I enjoy teaching Maths and have been extremely passionate about it since the start of my academic career. I am here to help students of an...”

You may also like...

Other A Level Maths questions

Can you differentiate the following function using two methods:- y = e^(2x+1)

A Definitive Guide to Differentiation

How do you integrate (sinx)^2?

The volume of liquid in a container is given by v=(3h^2+4)^(3/2)-8, find dV/dh when h = 0.6

View A Level Maths tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok