Java程序来查找二次方程的根
二次方程的根由以下公式确定：
$$x=\frac{-b\pm\sqrt[]{b^2-4ac}}{2a}$$
计算根-
计算行列式值（b*b）-（4*a*c）。
如果行列式大于0，则根为[-b+平方根（行列式）]/2*a和[-b-平方根（行列式）]/2*a。
如果行列式等于0，则根值为（-b+Math.sqrt(d)）/（2*a）
示例
import java.util.Scanner;
public class RootsOfQuadraticEquation {
public static void main(String args[]){
double secondRoot = 0, firstRoot = 0;
Scanner sc = new Scanner(System.in);
System.out.println("Enter the value of a ::");
double a = sc.nextDouble();
System.out.println("Enter the value of b ::");
double b = sc.nextDouble();
System.out.println("Enter the value of c ::");
double c = sc.nextDouble();
double determinant = (b*b)-(4*a*c);
double sqrt = Math.sqrt(determinant);
if(determinant>0){
firstRoot = (-b + sqrt)/(2*a);
secondRoot = (-b - sqrt)/(2*a);
System.out.println("Roots are :: "+ firstRoot +" and "+secondRoot);
}else if(determinant == 0){
System.out.println("Root is :: "+(-b + sqrt)/(2*a));
}
}
}输出结果
Enter the value of a :: 15 Enter the value of b :: 68 Enter the value of c :: 3 Roots are :: -0.044555558333472335 and -4.488777774999861