Question 813721
Decide whether each equation has a circle as its graph.  If it does, give the center and radius.

x2 + 6x + y2 + 8y + 9 = 0
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It's a circle.
x^2 + 6x + y^2 + 8y + 9 = 0
x^2 + 6x + y^2 + 8y = -9
Complete the square for x and y.
x^2 + 6x + 9 + y^2 + 8y + 16 = -9 + 9 + 16 = 16
{{{(x+3)^2 + (y+4)^2 = 16}}}
Center (-3,-4)
r = 4