How to complete the square to find the value of x?

To complete the square you compare your equation in the form x2 + bx + c = 0 to a similar equation of (x + b/2)2 + c = 0. From expanding out the second equation we have x2 + bx + (b/2)2 + c = 0 we can see this differs from the first equation by the term (b/2)2 so if we subtract (b/2)2 we are back to the original equation. So the equation x2 + bx + c = 0 is equal to (x + b/2)2 - (b/2)2 + c = 0. So to solve this we can move the terms around to get (x + b/2)2 = (b/2)2 - c which can then be solved by taking the square root of both sides.

AA
Answered by Ayotunde A. Maths tutor

3537 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

The number of uniform spherical balls that can be produced from a given mass of lead is inversely proportional to the radius of the ball cubed. If 2744 balls can be made when the radius is 1mm, how many balls can be made when the radius is 1.4mm ?


How do you solve a simultaneous equation?


Rearrange to make x the subject of the equation: 4(3x+y) = 12-2y


Solve the simultaneous equations; 3x + 2y = 11 x -4y = 13


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