The sign in $x-a$ has been reversed, so the coordinate is negative.

The answer is $(-5,3)$. We can see this as it is $x+5$ and $y-3$. The general equation contains $x-a$, so the reversal of the sign indicates that it is a negative coordinate.

The general equation for a circle contains $r^2$. Therefore, we need to find $\sqrt4$

Rearrange the order to get $x^2+2x+y^2+4y=20$.


First step would be to halve the coefficient of $y$ , which is $2$, and place it inside a squared bracket with $y$:$(y + 2)^2$. You then needed to minus  $(y + 2)$$4$  as expanding the brackets would be  $2  \times 2 =$  $4$ larger than original. Answer is:$(y + 2)^2 - 4$.  



You add $1 $ and $4$  on both sides to get rid of the numbers on the left side, and collecting it to the right side, so it becomes﻿: $(x+1)^2+(y+2)^2=25$  



The answer is $(-1, -2)$ . We can see this as it is $x + 1$ and $y + 2$. The general equation contains $x-a$ and $y + b$$y - b$,  so the reversal of the signs indicates that it is negative coordinates.


Completing the square for x gives $x^2 + 2x - 8 = (x + 1)^2 - 9$

Almost! But you forgot to square root 9 to find the radius.

Circles can be plotted on a graph from an equation in the same way as other functions. Finding the equation involves competing the square.

Equation of a Circle 1

The Sine Graph

The Cosine Graph

The Tangent Graph

Quadratic Graphs

Quadratic Graphs 2

Cubic Graphs

Equation of a Circle 2

Reciprocal Graphs

Graphical Solutions to Simultaneous Equations

Exponential Functions

Our mission: to make knowledge accessible for everyone

Visit our blog for GCSE tips, study hacks, and app updates. We cover GCSE maths, physics, and biology. Boost your exam prep and get motivated with AlbertTeen!

AlbertTeen UK Blog - GCSE, Study hacks and App updates

The baccalaureate is the national diploma that validates all your achievements and skills from high school. This is your passport to higher education!

Everything You Ever Wanted to Know About the 2023 GCSEs (But Were Afraid to Ask!)

With explanatory videos and educational exercises, the goal is closer than ever! Our content is designed so that you can easily study, set goals and finally master what has been challenging.

The content has been developed together with teachers and pedagogues and is based on research. You can start from your own level of knowledge and choose exactly the area you need to practice.

Are you looking to nourish your knowledge, sharpen your skills or perfect your performance? Albert Teen is here to help guide you to your target grade in GCSE Maths, Physics and Biology.

Pass the GCSE with a breeze! Revise with both web & phone apps. Our Maths, Physics & Biology exercises make it easy to revise & learn with hints & explanations

Interactive content with hints makes learning a breeze. Developed together with teachers and students. Albert Teen helps your teenager reach their goals in school!

Psstt.. If you want to save your progress and earn badges, download the app instead!

All of our GCSE exercises and activities are available for free whenever you need them. But if you want to save your progress, receive revision tips and earn badges to prove your progress, download the app today.

GCSE Revision - Free. Online. Any Time.

Follows the curriculum

Is there anything better than breezing through an exam? Take control of your studies with the Albert Teen App and experience that winning feeling over and over again.

Our users love Albert Teen. Here’s a few examples of why:

Albert teen makes studying for the GCSE exams fun & easy.

The Perfect Virtual Tutor to Help You Pass Your GCSE Exams

powered by

For each area there are several explanatory videos that cleverly go through the rules and examples. In addition, there is a function that gives the child tips if he gets stuck on a task.