Java Math for Engineers - JAVA Programming for Engineers - page 282

2

ax ++= bx c 0

where the coefficients a , b , and c are constants. The solution a quadratic
equation can be attempted by applying the standard quadratic formula:

2

−± − bbc 4

x =

2 a

In the quadratic equation the term

2

bc −

is called the discriminant. The value of the discriminant is used to deter-
mine if the solution set has two equal real roots, two different real roots, or
no real roots. The following programattempts to find the real roots of a qua-
dratic equation (if they exist) by solving the quadratic formula.

// Java for Engineers
// Filename: QuadSolv
// Reference: Chapter 24
// Description:
// Applying the quadratic formula

// Requires:
// Keyin class in current directory

import java.lang.*;

strictfp class QuadSolv
{

public static void main(String[] args)
{

double a, b, c, discr, root1, root2;

// Apllying the quadratic formula
// Obtain sides from user
System.out.println(“Applying the quadratic formula”);
a = Keyin.inDouble(“Enter a: ”);
b = Keyin.inDouble(“Enter b: ”);
c = Keyin.inDouble(“Enter c: ”);

// Solve the discriminant (SQRT (b^2 - 4ac)
discr = Math.sqrt((b * b) - (4*a*c));
System.out.println(“Discriminant=”+discr);
// Determine number of roots