import math

def quadratic(a, b, c):

    delta = b**2-4*a*c

    if delta < 0:

        return '该二元一次方程无解'

    if delta >= 0:

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

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

        return x1, x2

# 测试:

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')

a=float(input('a='))

b=float(input('b='))

c=float(input('c='))

print('result:',quadratic(a,b,c))