How do you graph x^2+y^2+3x-6y+9=0x2+y2+3x6y+9=0?

1 Answer
Mar 5, 2016

circle : centre( -3/2 , 3 ) , " radius " = 3/2 (32,3), radius =32

Explanation:

The general form of the equation of a circle is :

x^2 + y^2 + 2gx + 2fy + c = 0 x2+y2+2gx+2fy+c=0

centre = (-g,-f) and r = sqrt(g^2+f^2 - c )g2+f2c

x^2 + y^2 + 3x - 6y + 9 = 0 " is in this form "x2+y2+3x6y+9=0 is in this form

and by comparison : 2g = 3 → g =3/2=32, 2f = -6 → f = -3, c=9

centre = (-3/2 ,3 )" and " r = sqrt((3/2)^2+(-3)^2-9)=3/2(32,3) and r=(32)2+(3)29=32