Solve x^2+8x-5 = 0 by completing the square.

x2 + 8x = (x + 4)2 - 16, so x2 + 8x - 5 = (x + 4)2 - 16 - 5 = (x + 4)2 - 21, so then (x + 4)- 21 = 0 (x + 4)= 21 -----> x + 4 = √21 -------> x = -4 + √21                               x = -4 - √21

Answered by Shadab J. Maths tutor

10733 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

How to solve a simultaneous equation?


Rearrange aq - ac = d


There are only red , blue and purple counters in a bag. The ratio of the number of red counters to the number of blue counters is 3 : 17. If a counter is taken randomly the probability that it is purple is 0.2 Work out the probability for it to be red.


Make x the subject of the formula when: y = 6-2x / 8


We're here to help

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

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences