Question

A.P.34+32+30...........+10

Answer 1

Answer:

here 1st term is 34

common difference is 32-34= -2

let 10 is the nth term

10=34+(n-1).(-2)

10=34-2n+2

10=36-2n

2n=36-10=26

n=26/2=13

sum of 13 th term is

13/2{2.34+(13-1). -2}

=13/2{68-24}

=13/2×44

=13×22

=286

Answer 2

Given:-

a = 34 , d = - 2 , l = 10

We know that,

Sn = n/2 ( a + l)

We have to find out n =?..

An = a + ( n - 1) d

10 = 34 + ( n- 1) (- 2)

10 = 34 - 2n + 2

10 = 36 - 2n

- 26 = - 2n

n = 13.

S13 = 13/2 ( 34 + 10)

S13 = 13/2 x 44

S13 = 13 x 22

S13 = 286.

BTS AND EXO