﻿ The fifth terms of an A.P. is 1 whereas its 31st term is – 77. Find its 20th term and sum of its first fifteen terms. Also find which term of the series will be  –17 and sum of how many terms will be 20. : Kaysons Education

# The Fifth terms Of An A.P. Is 1 Whereas Its 31st Term Is – 77. Find Its 20th Term And Sum Of Its First Fifteen Terms. Also Find Which Term Of The Series Will Be  –17 And Sum Of How Many Terms Will Be 20.

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## Question

### Solution

Correct option is

n = 8

.

Solving the above two, we get

a = 13 and d = –3.                … (i)

Let    Tn = –17. Then a + (n – 1)d = –17

.

.

.

The value of n cannot be fractional.

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