When the equation x + y + DX + ey + F = 0 satisfies what condition, it means circle

x^2+y^2+dx+ey+f=0
(x+d/2)^2+(y+e/2)^2=1/4(d^2+e^2)-f
When 1 / 4 (d ^ 2 + e ^ 2) - F > 0, it means a circle with (- D / 2, E / 2) as the center and √ [1 / 4 (d ^ 2 + e ^ 2) - F] as the radius

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