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

3767 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

There are a total of 50 apples and pears (apples + pears) in a large basket. If the total number of apples was doubled and the total number of pears was tripled, these two numbers would add up to 130. How many apples and pears are in the basket?


Write 2x^2 + 16x + 26 in the form a(x + d)^2 + e where a, d, and e are integers.


How do you find the turning point of a quadratic equation?


How do I draw a straight line graph given a y=mx+c equation by the table method?


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