Hello from MrBillDoesMath!
Answer:
Center = (-4,3)
radius = 4
Discussion:
x^2 + y^2 + 8x -6y + 9 = 0
Let "complete the square" for the x and y terms:
x^2 + y^2 + 8x -6y + 9 = 0 => group like terms
(x^2 + 8x ) + (y^2 - 6y) + 9 = 0 => complete the square for x, y
(x^2 + 8x + 16) + ( y^2 - 6y + 9) -16 - 9 +9 = 0 =>
(x+4)^2 + ( y-3)^2 = 16 + 9 - 9 =>
(x+4)^2 + ( y-3)^2 = 16 =>
Therefore,
radius = sqrt(16) = 4,
Center = (-4,3)
Graph of function attached.
Thank you,
MrB