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

Related Maths GCSE answers

All answers ▸

Solve the simulaneous Equations: 5x + y = 21, x - 3y = 9


Show that ((sqrt(18)+sqrt(2))^2)/(sqrt(8)-2) can be written in the form a(b + 2) where a and b are integers.


What is solution by substitution?


How to solve the inequality 4(x+3) < 60?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo
Cookie Preferences