package com.yirose.java8.string;

public class CalculateRoot {

    public static void main(String[] args) {

        //解：求一元二次方程ax2+bx+c=0的根的算法步骤是

        // [Step 1] 输入3个系数a，b，c；

        int a = 5;

        int b = 11;

        int c = 5;

        // [Step 2] 计算△=b2-4ac；

        int v = (int) Math.pow(b, 2) - 4 * a * c;

        // [Step 3] 判断 △ ≥ 0是否成立;

        if (a == 0 && b == 0 && v < 0) {

            System.out.println("方程不成立或方程没有实数根，请重新输入:");

        } else {

            double p = b / (2 * a);

            double q = Math.sqrt(v) / (2 * a);

            // [Step 4];

            if (v == 0) {

                System.out.println("x1=x2=" + p);

            } else {

                System.out.println("x1=p+q x1=" + (p + q));

                System.out.println("x2=p-q x2=" + (p - q));

            }

        }

    }

}