721 views

### 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

1 year ago

Answered by Reuben, a GCSE Maths tutor with MyTutor

## Still stuck? Get one-to-one help from a personally interviewed subject specialist

#### 782 SUBJECT SPECIALISTS

£18 /hr

Degree: Mathematics (Bachelors) - Bath University

Subjects offered:Maths, Further Mathematics + 1 more

Maths
Further Mathematics
-Personal Statements-

“An engaging, creative and friendly tutor with 4 years experience in tutoring Maths to a broad range of ages and abilities.”

Trusted by schools

|  4 completed tutorials

£18 /hr

Degree: Environmental Geoscience (Bachelors) - Durham University

Subjects offered:Maths, Geology+ 2 more

Maths
Geology
Geography
Chemistry

“Third year Earth Sciences student at Durham; specialise in geochemistry and tutor in Earth sciences, Chemistry and Maths”

Trusted by schools

|  4 completed tutorials

£20 /hr

Degree: Economics (Bachelors) - Cambridge University

Subjects offered:Maths, Economics+ 2 more

Maths
Economics
-Personal Statements-
-Oxbridge Preparation-

“Economics Graduate from Cambridge, wanting to share my passion for the discipline”

£18 /hr

Degree: Maths (Masters) - York University

Subjects offered:Maths, Further Mathematics

Maths
Further Mathematics

“About Me I am a maths student at University of York. I have had a love for maths and all it's complexity ever since I was little and I aspire to make others love maths as I do. I am a qualified basketball coach and have been teaching...”

MyTutor guarantee

### You may also like...

#### Other GCSE Maths questions

3x^2 + 7x - 13 = 0. What is x?

Factorise and solve: x^2 - 8x = -15

How to solve simultaneous equations with two unknowns?

Surd Calculations?

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this.