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

3612 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Find the area of a kite with length 12cm and height 6cm.


A lorry can travel 35 miles per litre of diesel that costs £7.30 per litre. What is the cost in £ (to the nearest 2 decimal places) of the diesel used in driving the lorry 200 miles?


Solve the simultaneous equations algebraically.


how would you expand quadratic factors


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