def quadratic(a, b, c=0):

mt = (a, b, c)

for num in mt:

if isinstance(num, (int, float)):

if ((b**2) - (4 * a * c)) >= 0: 

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

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

if x1 == x2:

x = x1

else:

x = (x1, x2)

else:

x = 'no result'

else:

x = '请输入正确的格式'

return x

a = eval(input('x^2的系数：'))

b = eval(input('x的系数: '))

c = eval(input('常数：'))

x = quadratic(a, b, c)

print('方程的解为：{}'.format(x))