Given a number N, the task is to find the Nth term of the following series.
-2, 4, -6, 8……
Examples:
Input: n=4 Output: 8 Input: n=3 Output: -6
Approach: By clearly examining the series we can find the Tn term for the series and with the help of tn we can find the desired result.
Tn=-2 + 4 -6 +8 …..
We can see that here odd terms are negative and even terms are positive
Tn=2(-1)nn
Tn=(-1)n2n
Below is the implementation of above approach.
CPP
// C++ implementation of the approach#include <bits/stdc++.h>using namespace std;// Function to return the// nth term of the given serieslong Nthterm(int n){ // nth term int Tn = pow(-1, n) * 2 * n; return Tn;}// Driver codeint main(){ int n = 3; cout << Nthterm(n); return 0;} |
Python
# Python3 implementation of the approach # Function to return the nth term of the given series def Nthterm(n): # nth term Tn = ((-1)**n) * (2 * n) return Tn; # Driver code n = 3print(Nthterm(n)) |
Java
// Java implementation of the approachimport java.util.*;import java.lang.*;import java.io.*;public class GFG { // Function to return the nth term of the given series static int NthTerm(int n) { int Tn = ((int)Math.pow(-1, n)) * 2 * n; return Tn; } // Driver code public static void main(String[] args) { int n = 3; System.out.println(NthTerm(n)); }} |
C#
// C# implementation of the approachusing System;public class GFG { // Function to return the nth term of the given series static int NthTerm(int n) { int Tn = ((int)Math.Pow(-1, n) * 2 * n); return Tn; } // Driver code public static void Main() { int n = 3; Console.WriteLine(NthTerm(n)); }} |
PHP
<?php // PHP implementation of the approach // Function to return the nth term of the given series function Nthterm($n) { $Tn = (pow(-1, $n)) * (2*n); // nth term of the given series return $Tn; } // Driver code $n = 3; echo Nthterm($n); ?> |
Javascript
<script>// JavaScript implementation of the approach// Function to return the// nth term of the given seriesfunction Nthterm( n){ // nth term let Tn = Math.pow(-1, n) * 2 * n; return Tn;}// Driver Function // get the value of N let N = 3; // Calculate and print the Nth term document.write( Nthterm(N));// This code is contributed by todaysgaurav </script> |
Output:
-6
Time Complexity: O(log n)
Auxiliary Space: O(1)
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