Question

find the sum of the following series:-
2+5+6+.......to 40 terms. please answer fast

Answer 1

a = 2
sum = 38/2 (2 + 40)
= 19 × 42
= 798

I hope it is clear for you. Ask me if you have any doubts and don't forget to mark my answer as the brainliest answer.

Answer 2

The given series is in arithmetic progression.

Here a1 = 2



d = a2 - a1 = 4 - 2 = 2


an = 40

To find the sum of given numbers, first we need to find how many terms are there in the series. So, we need to find n value.



an = a + (n-1)d


40 = 2 + (n-1)2 = 2 + 2n - 2 = 2n
n = 40/2 = 20

Now we need to find sum of 24 terms i.e. S20


Sn = n/2 ( a1 + an)
S20 = 20/2 (2+ 40)
S20 = 10×42
= 420 Ans

It's helpful for you