def quadratic(a, b, c): m = b b - 4 a c if m > 0: x1 = 0.5 (math.sqrt(m) - b) / a x2 = 0.5 (-math.sqrt(m) - b) / a print(x1, x2) elif m == 0: x1 = -0.5 b / a x2 = -0.5 * b / a print(x1, x2) else: print('无解')

    这个文件保存为test.py，然后from test import quadratic，也是可以用的，为啥？