import math

def quad(a,b,c):
  if a==0.0:
    if b==0.0:
      return None
    return (-c/b,)

  if b**2-4.0*a*c <0:
    return None

  if b < 0.0: 
    return ((-b + math.sqrt(b**2-4.0*a*c))/2.0/a,2.0*c/(-b + math.sqrt(b**2 - 4.0*a*c)))
  else:
    return (2.0*c/(-b - math.sqrt(b**2-4.0*a*c)),(-b - math.sqrt(b**2 - 4.0*a*c))/2.0/a)



print quad(0,0,0)
print quad(0,1,4)
print quad(1,1,1)
print quad(1,-100000000000000,1)
print quad(1,-10,1)