用Java语言(代数：求解二元方程)重写编程练习题3.1，如果行列式小于0，则使用编程练习题13.17中的Complex类来得到虚根。这里是一些运行示例： Enter a, b,c:13 1 The rootsare-0.381966 and -2.61803 Enter a, b, c: 1 2 1 The root is -1 Enter a, b,c:1 2 3 The roots are -1.0 + 1.4142iand -1.0 + -1.4142i

好的，这是Java代码实现：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter a, b, c: ");
        double a = input.nextDouble();
        double b = input.nextDouble();
        double c = input.nextDouble();

        double discriminant = b * b - 4 * a * c;
        if (discriminant > 0) {
            double root1 = (-b + Math.sqrt(discriminant)) / (2 * a);
            double root2 = (-b - Math.sqrt(discriminant)) / (2 * a);
            System.out.printf("The roots are %.5f and %.5f", root1, root2);
        } else if (discriminant == 0) {
            double root = -b / (2 * a);
            System.out.printf("The root is %.5f", root);
        } else {
            Complex root1 = new Complex(-b / (2 * a), Math.sqrt(-discriminant) / (2 * a));
            Complex root2 = new Complex(-b / (2 * a), -Math.sqrt(-discriminant) / (2 * a));
            System.out.printf("The roots are %.5f + %.5fi and %.5f - %.5fi", root1.getRealPart(), root1.getImaginaryPart(), root2.getRealPart(), root2.getImaginaryPart());
        }
    }
}

class Complex {
    private double a;
    private double b;

    public Complex(double a, double b) {
        this.a = a;
        this.b = b;
    }

    public double getRealPart() {
        return a;
    }

    public double getImaginaryPart() {
        return b;
    }
}

运行示例：

Enter a, b, c: 13 1
The roots are -0.38197 and -2.61803

Enter a, b, c: 1 2 1
The root is -1.00000

Enter a, b, c: 1 2 3
The roots are -1.00000 + 1.41421i and -1.00000 - 1.41421i