import math

def quadratic_equation(a, b, c):

? ? if (b*b-4*a*c) >= 0:

? ? ? ? x1=(math.sprt(b*b-4*a*c)-b)/(2*a)

? ? ? ? x2=(-(math.sprt(b*b-4*a*c)-b)/(2*a)

? ? ? ? return x1,x2

? ? else:?

? ? ? ? return None

print quadratic_equation(2, 3, 0)

print quadratic_equation(1, -6, 5)