2.6

package booksTest;

import seventh.ScannerFileTest;

import java.util.Scanner;

public class p34_2_6 {
    public static void main(String[] args) {
       /*
       题目要求
          编写程序 ，要求用户从键盘输入a 、b 、和c的值，计算下列表达式的值
        */
        Scanner sc = new Scanner(System.in);
        for (int i = 0; i <10 ; i++) {
             System.out.println("请输入a的值");
            double a = sc.nextDouble();
            System.out.println("请输入b的值");
            double b = sc.nextDouble();
            System.out.println("请输入c的值");
            double c = sc.nextDouble();
            double e = Math.sqrt(b * b - 4 * a * c);
            double f = -b + e;
            if (e > 0) {
                System.out.println("表达式的值为" + f / 2 * a);
                return;
            } else {
                System.out.println("你输入的值b^2-4ac小于0");
        }
        }
    }
}