Solve "x^2 - 12x - 45 = 0" by completing the square

The equation is of the formx2+bx+c=0This means it can be rearranged to(x+(b/2))2=(b/2)2-cTaking the square root of both sides leaves us with x.
x2-12x-45=0(x-(12/2))2-(12/2)2-45 = 0(x-6)2-62-45 = 0(x-6)2 = 45 + 36(x-6)2 = 81x-6 = 9x= 6 + 9 = 15

EJ
Answered by Elsa J. Maths tutor

6778 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

3 teas and 2 coffees have a total cost of £7.80. 5 teas and 4 coffees have a total cost of £14.20. Work out the cost of one tea and the cost of one coffee.


What are the different methods of solving quadratic equations?


Work out 2 7/15 -1 2/3


Solve the inequality: 5x-3 < 7x-6


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