# Program to find the nth term of the series -2, 4, -6, 8….

• Last Updated : 23 Jun, 2022

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)n
Tn=(-1)n2n

Below is the implementation of above approach.

## CPP

 `// C++ implementation of the approach` `#include ``using` `namespace` `std;` `// Function to return the``// nth term of the given series``long` `Nthterm(``int` `n)``{` `    ``// nth term``    ``int` `Tn = ``pow``(-1, n) * 2 * n;` `    ``return` `Tn;``}` `// Driver code``int` `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 ``=` `3``print``(Nthterm(n))`

## Java

 `// Java implementation of the approach``import` `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 approach``using` `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

 ` `

## Javascript

 ``

Output:

`-6`

Time Complexity: O(log n)

Auxiliary Space: O(1)

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