为什么不用判断是否有根？直接运算？

import math

def quadratic_equation(a, b, c):
    t = math.sqrt(b * b - 4 * a * c)
    return (-b + t) / (2 * a), (-b - t ) / (2 * a)


print quadratic_equation(2, 3, 0)
print quadratic_equation(1, -6, 5)

qq_慕工程9421730

2020-02-07

源自：初识Python 7-4

关注问题我要回答

515

操作

收起

1 回答

qq_慕盖茨2477813
2020-02-07

有道理，确实应该先判断b*b-4*a*c>=0,要不然就运算错误了。

import math
def quadratic_equation(a, b, c):
    if   (b * b - 4 * a * c)>=0:
        t = math.sqrt(b * b - 4 * a * c)
        return (-b + t) / (2 * a), (-b - t ) / (2 * a)
    else:
        return "import ERROR"
print quadratic_equation(2, 3, 9)
print quadratic_equation(1, -6, 5)