package com.itranswarp.learnjava;

/**

 * 求解 一元二次方程ax^2+bx+c=0

 */

public class Main {

public static void main(String[] args) {

// x*x + 3*x - 4 = 0

double a = 1.0;

double b = 3.0;

double c = -4.0;

// 求平方根可用 Math.sqrt():

// double x = Math.sqrt(2)); // ==> 1.414

// TODO:

double d = Math.sqrt(b*b-4*a*c);

double r1 = (-b+d)/2/a;

double r2 = (-b-d)/2/a;

System.out.println(r1 + ", " + r2);

System.out.println(r1 == 1 && r2 == -4 ? "测试通过" : "测试失败");

}

}