How do I solve a quadratic equation by competing the square?

How would you solve  x2+8x+16=81Show that this can be factorised (x+4)2=92Which can then be easily solved by square rooting both sides
What if we could now use this method to solve all quadratics?!!?
Consider Solve  x2+6x+1=0
We can complete the square by:(x+3)2-9+1=0 (x+3)2-8=0 (x+3)2=8 (x+3)=±√8 x=-3±2√2

Answered by Maths tutor

3443 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

I struggle with simultaneous equations, when you have a quadratic involved


If a cuboid of width and height-8m with a volume of 896m^3, work out the length of the cuboid and distance between two opposite points


What does it mean to solve an equation for x?


Prove that the square of an odd number is always 1 more than a multiple of 4


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