#!/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))