import math

def quadratic(a, b, c):
    for x in (a, b, c):
        if not isinstance(x, (int, float)):
            raise TypeError("type error")
    y = b ** 2 - 4*a*c
    if y < 0:
        print("方程无实根!")
    elif y == 0:
        res = -b/2*a
        print("方程只有一个实根 %s" % str(res))
    else:
        res1 = (-b + math.sqrt(y))/2*a
        res2 = (-b - math.sqrt(y))/2*a
        print("方程有两个实根，分别是 %s, %s" % (str(res1), str(res2)))