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

6954 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Solve the quadratic equation x^2+5x+6=0


solve z^4=2(1+isqrt(3)) giving roots in form r(cos(theta)+isin(theta))


A sequence increases by 5 each time and the first term is x. The sum of the first four terms is 54. Set up and solve an equation to work out the value of x.


How to find the roots of a Quadratic Equation by Factorising?


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