import math
def quadratic(a,b,c):
    if not isinstance(a,(float,int)) or a ==0:
        raise TypeError("'a' has mistake ")
    if not isinstance(b,(float,int)):
        raise TypeError("a b c mistake")
    if not isinstance(c,(float,int)):
        raise TypeError("a b c mistake")
    n = math.sqrt(b**2-4*a*c)
    if n < 0:
        print("无解")
    else:
        x = (-b+n)/(2*a)
        y = (-b-n)/(2*a)
        return x,y
print('quadratic(2,3,1) =',quadratic(2,3,1))
print('quadratic(1, 3, -4) =', quadratic(1, 3, -4))
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')