如何在c ++中求具有负根的二次方程解？

#include <iostream>
#include <cmath>

int main() {
    double a, b, c;
    std::cout << "请输入二次方程的系数a, b, c: ";
    std::cin >> a >> b >> c;

    double discriminant = b * b - 4 * a * c;

    if (discriminant > 0) {
        double root1 = (-b + sqrt(discriminant)) / (2 * a);
        double root2 = (-b - sqrt(discriminant)) / (2 * a);
        std::cout << "方程有两个不相等的实数根: " << root1 << " 和 " << root2 << std::endl;
        if (root1 < 0 || root2 < 0) {
            std::cout << "至少有一个负根。" << std::endl;
        }
    } else if (discriminant == 0) {
        double root = -b / (2 * a);
        std::cout << "方程有一个重根: " << root << std::endl;
        if (root < 0) {
            std::cout << "根是负数。" << std::endl;
        }
    } else {
        std::cout << "方程没有实数根，它有一对共轭复数根。" << std::endl;
    }

    return 0;
}