java求一元二次方程+y=ax2+bx+c+的实数根。

以下是Java求解一元二次方程的代码示例：

import java.util.Scanner;

public class QuadraticEquation {
    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.println("The roots are " + root1 + " and " + root2);
        } else if (discriminant == 0) {
            double root = -b / (2 * a);
            System.out.println("The root is " + root);
        } else {
            System.out.println("The equation has no real roots.");
        }
    }
}

用户需要输入方程的系数a、b、c，程序会根据判别式的值来输出方程的实数根。如果判别式大于0，则方程有两个实数根；如果判别式等于0，则方程有一个实数根；如果判别式小于0，则方程无实数根。