How do you simplify the square root of 18 without using a calculator?

Surds can be simplified if the number in the square root has a square number as a factor. It is also worth remembering that SQRT(ab) = SQRT(a) x SQRT(b). So if you combine these two points, lets look at how we can simplify the square root of 18.

A factor of 18 that is a square number is 9. Therefore SQRT(18) = SQRT(9) x SQRT(2). The square root of 9 is 3, so we can now write our final answer as SQRT(18) = 3 x SQRT(2). To check you’ve understood this, you might like to have a go at simplifying these two surds. A) SQRT(20)  B) SQRT(32)

RB
Answered by Richard B. Maths tutor

4692 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Expand (x+4)(x+3).


Solve x^2+6x+1=0 by completing the square


i) Make y the subject of the expression x = ((a-y)/b))^1/2 ii) Simplify fully (2x^2 − 8)/(4x^2 − 8x)


How do I factorise quadratic equations into brackets?


We're here to help

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

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences