#!/usr/bin/env python3

# -*- coding: utf-8 -*-

import math

def quadratic(a, b, c):

if math.sqrt(b*b-4*a*c)>0:

x1=(-b+math.sqrt(b*b-4*a*c))/(2*a)

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

return x1, x2

elif math.sqrt(b*b-4*a*c)==0:

x1=-b/(2*a)

x2=x1

return x2

else:

x = '无解'

return x

print('quadratic(2, 3, 1) =', quadratic(2, 3, 1))

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

if quadratic(2, 3, 1) != (-0.5, -1.0):

print('测试失败')

elif quadratic(1, 3, -4) != (1.0, -4.0):

print('测试失败')

else:

print('测试成功')