Question

the sum of n terms of series 25 ,22,19,16 .....is 116 find the nom of terms and last term​

Answer 1

Answer:

n = 9.6 or n = 8

but we take n = 8

last term = 4

Step-by-step explanation:

we solve this by using tn and sn

Tn = a + (n-1) d

a = 25

d = 22 - 25 = -3

so

Tn = 25 -3 (n-1)

now

Sn = n/2 [ 25 ×2 - 3 (n-1) ]

Sn = 116

on solving we get n

n = 8 as 1 root use that root put it in Tn you get last term as

T8 = 25 - 21 = 4

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