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)
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