Question

plz calculate thr sum of the folowing series.....java program using while loop plzz or else just tell the logic..plzz tryna send thr code too plzx....thanks​

Answer 1

Series Sum - Java

Question

Calculate the sum of the following series using a Java program, upto n terms.

$\sf 1.\ x+x^2+x^3+\dots \\ 2.\ x-x^2+x^3-\dots\\ 3.\ a-2a+3a-\dots$

Answer

We start by creating a Scanner object to take user input. We provide the user with a choice. Once a series is chosen from the menu, we employ the switch construct of Java.

For each series, the $\sf m^{th}$ can be written down as follows:

$1.\quad\sf T_m = x^m \\ 2.\quad\sf T_m = (-1)^{m+1}\ x^m \\ 3.\quad\sf T_m = (-1)^{m+1}\ ma$

For the alternate negative signs, we use the powers of -1. In Java, we use the $\tt Math.pow()$ method to get the exponents.

We initialize a Sum variable to 0. Then, we add each of the n terms to it and finally display the Sum.

$\rule{300}{1}$

Program Code: BrainlySeriesSum.java

import java.util.Scanner;

public class BrainlySeriesSum {

   public static void main(String[] args) {

       // Create Scanner object

       Scanner sc = new Scanner(System.in);

       // Menu

       System.out.println("---Series Sum Menu---");

       System.out.println("1. S = x + x^2 + x^3... upto n terms");

       System.out.println("2. S = x - x^2 + x^3... upto n terms");

       System.out.println("3. S = a - 2a + 3a - 4a ... upto n terms");

       // Take user input of choice

       System.out.print("\nEnter your choice [1/2/3]: ");

       String choice = sc.next();

       int n;              // Number of terms

       double Sum = 0;     // Initialize Sum to 0

       double x = 0;

       double a = 0;

       // Begin Switch Construct

       switch(choice) {

           case "1":

               System.out.print("Enter value of x: ");

               x = sc.nextDouble();

               System.out.print("Enter value of n: ");

               n = sc.nextInt();

               

               for(int i = 1; i <= n; i++) {

                   Sum += Math.pow(x, i);     // x + x^2 + x^3 + ...

               }

               System.out.println("Sum = "+Sum);

               break;

           case "2":

               System.out.print("Enter value of x: ");

               x = sc.nextDouble();

               System.out.print("Enter value of n: ");

               n = sc.nextInt();

               Sum = 0;

               

               for(int i = 1; i <= n; i++) {

                   Sum += Math.pow(-1, i + 1) * Math.pow(x, i);    // x - x^2 + x^3 + ...

               }

               System.out.println("Sum = "+Sum);

               

               break;

           

           case "3":

               System.out.print("Enter value of a: ");

               a = sc.nextDouble();

               System.out.print("Enter value of n: ");

               n = sc.nextInt();

               Sum = 0;

               

               for(int i = 1; i <= n; i++) {

                   Sum += Math.pow(-1, i + 1) * (i * a);   // a - 2a + 3a - ...

               }

               System.out.println("Sum = "+Sum);

               

               break;

           

           default:

               System.out.println("Invalid choice");

       }

       

       sc.close();

   }

}

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