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

3437 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Solve 4(x–5)=18


Solve for x : 2x-15=-2x-7


Determine the nature of the roots of the quadratic equation x^2 + 6x + 8 = 0, and plot the graph of this function.


How to find LCM and HCF of two numbers


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