RootsOfQuaeq.java

// Java program to find the roots of
// quadratic equation

public class RootsOfQuaeq {

	public static void main(String[] args)
	{

		// value of the constants a, b, c
		double a = 7.2, b = 5, c = 9;

		// declared the two roots
		double firstroot, secondroot;

		// determinant (b^2 - 4ac)
		double det = b * b - 4 * a * c;

		// check if determinant is greater than 0
		if (det > 0) {

			// two real and distinct roots
			firstroot = (-b + Math.sqrt(det)) / (2 * a);
			secondroot = (-b - Math.sqrt(det)) / (2 * a);

			System.out.format(
				"First Root = %.2f and Second Root = %.2f",
				firstroot, secondroot);
		}

		// check if determinant is equal to 0
		else if (det == 0) {

			// two real and equal roots
			// determinant is equal to 0
			// so -b + 0 == -b
			firstroot = secondroot = -b / (2 * a);

			System.out.format(
				"First Root = Second Root = %.2f;",
				firstroot);
		}

		// if determinant is less than zero
		else {

			// roots are complex number and distinct
			double real = -b / (2 * a);

			double imaginary = Math.sqrt(-det) / (2 * a);

			System.out.printf("First Root = %.2f+%.2fi",
							real, imaginary);
			System.out.printf("\nSecond Root = %.2f-%.2fi",
							real, imaginary);
		}
	}
}