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)2x2-4x+4=x2+12x+36-16x=32x=-2This 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|.​

MF
Answered by Michael F. Maths tutor

31626 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

How do you find an angle in a right-angled triangle when you are given two of its side's lengths?


How do you differentiate y=x^x?


Find two positive numbers whose sum is 100 and whose product is a maximum.


How do I get the eigenvalues, x, of a matrix, M, with eigenvectors, v?


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2026 by IXL Learning