-- coding: utf-8 --

import math

def quadratic(a, b, c):

dt = b**2 - 4*a*c

if a == 0:

    x = (-c)/b

    return x

elif dt < 0:

    return '方程无实数根'

else:
    x1 = (-b + math.sqrt(dt))/(2*a)

    x2 = (-b - math.sqrt(dt))/(2*a)

    return x1, x2

pass

print(quadratic(2, 3, 1))

print(quadratic(1, 3, -4))