!/usr/bin/env python3

-- coding:utf-8 --

import math def quadratic(a, b, c): '解一元二次方' if a == 0:

    # a == 0:原方程式变成一元一次方 bx+c=0
    if b == 0:
        # b == 0，原方程式为 c=0 ，不合常理，抛出异常
        return 'a等于0时，b不能等于0'
    else:
        return  (-c/b,-c/b)
else:
    # a != 0
    delta = b**2 -4*a*c
    if delta >= 0:
        return ((-b + math.sqrt(delta))/(2*a),(-b + math.sqrt(delta))/(2*a))
    else:
        return 'delta < 0 ,方程式无解！'

if name == "main": print(quadratic(2, 3, 1)) print(quadratic(1, 3, -4))