Hi,

x2+y2+16x+6y+9=0

x2+y2+16x+6y = -9    ||Completing the Square

(x+8)^2 + (y + 3)^2 = -9 + 64 + 9



(x+8)^2 + (y + 3)^2 = 64   C (-8,-3), Circle with r = 8

Standard Form of an Equation of a Circle is  

where Pt(h,k) is the center and r is the radius

 

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