Question

If the 1" term of an A.P. is 25. Find the Sum of its first 41
terms. d= 2​

Answer 1

Solution:

Given:

=> a = 25

=> d = 2

To Find:

=> Sum of first 41 terms.

Formula used:

$\sf{\implies S_{n}=\dfrac{n}{2}[2a+(n-1)d]}$

So, Put the values in the formula we get,

$\sf{\implies S_{41}=\dfrac{41}{2}[2\times 25+(41-1)2]}$

$\sf{\implies \dfrac{41}{2}[50+80]}$

$\sf{\implies \dfrac{41}{2}[130]}$

$\sf{\implies 2665}$

So, the sum of first 41 terms is 2665.