How do you graph x2+y2+6x8y+9=0?

1 Answer
Feb 12, 2016

circle: centre(-3 , 4) and radius = 4

Explanation:

the general equation of a circle is

x2+y2+2gx+2fy+c=0

the equation here : x2+y2+6x8y+9=0
compares with the general equation and is therefore a circle.

by comparison of the 2 equations :

obtain: 2g = 6 → g = 3 , 2f = -8 → f = -4 and c = 9

centre = (-g , -f ) = (-3 , 4 )

and radius = g2+f2c=(3)2+429=16=4