#!/usr/bin/env python

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

 import math

 def quadratic(a,b,c):

     if a == 0:

         raise TypeError('a不能为0')

     if not isinstance(a,(int,float)) or  not isinstance(b,(int,float)) or not isinstance(c,(int,float)):

         raise TypeError('Bad operand type')

     delta = math.pow(b,2) - 4*a*c

     if delta < 0:

         return '无实根'

     x1= (math.sqrt(delta)-b)/(2*a)

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

     return x1,x2

 print(quadratic(2,3,1))

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