x^2 + y^2 + 6x=0. How would I go about finding the radius and center? What's the basic method?
-Thanks!
Hello,
To complete the squares
I'll do it in a newly way to me... lol
$\displaystyle x^2+6x=x(x+6)=((x+3)-3)((x+3)+3)=(x+3)^2-3^2=(x+3)^2-9$
(I know you can do it in a shorter way... find it ! )
Hence the equation becomes :
$\displaystyle (x+3)^2+y^2-9=0 \Longleftrightarrow (x+3)^2+y^2=9$
We know that the equation of a circle, center $\displaystyle O(x_O,y_O)$ and radius R is :
$\displaystyle (x-x_O)^2+(y-y_O)^2=R^2$
Conclude