How do you graph x2+y2+4x−4y−1=0?
1 Answer
Feb 15, 2016
circle: centre =(-2 ,2) , r = 3
Explanation:
The general equation of a circle is
x2+y2+2gx+2fy+c=0 the equation here :
x2+y2+4x−4y−1=0 is in this form by comparison: 2g = 4 → g = 2 , 2f = -4 → f=-2 and c = -1
centre = (-g , -f) = (-2 , 2)
and r
=√g2+f2−c=√22+(−2)2+1=√9=3