A circle with centre C has equation x^2 + y^2 + 2x - 6y - 40 = 0. Express as (x - a)^2 + (y - b)^2 = d.

First we must complete the square on both x and y. To complete a square we must take the number before the x and half it, for example nx we get n/2. We then write it as (x + n/2)- (n/2)2

So for our question we have 2x so we will write (x + 1)2 - (1)2. Then we repeat for y. We have -6y so we will write (y - 3)2 - (3)2.

We then write all of this together as (x + 1)2 - 1 + (y - 3)2 - 9 - 40 = 0. Rearrange and we get (x + 1)+ (y - 3)2  = 50

RM
Answered by Reuben M. Maths tutor

7761 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

Simplify: 5x + 8y - 3x + 9y


Dominik hires a satellite phone. His total hire charge is £860. For how many weeks did he hire the phone? (Total hire charge = No. of week X 90 +50)


Express x*2 + 10x - 3 in the form (x+p)*2 + q


multiply out (2x-4)(x-2) and simplify.


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:

© 2025 by IXL Learning