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

3452 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

A cuboid has sides such that the longest side is two units more than the shortest side, and the middle length side is one unit longer than the shortest side. The total surface area of the cuboid is 52 units². What is the length of the shortest side?


Solve the simultaneous equations: 3x+4y=19, x-6y= -23.


Solve x^2 = 4(x - 3)^2


Solve algebraically: 6a + b = 16 5a - 2b = 19


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