Q. 29

In an A.P. the first term is 2, and the sum of the first 5 terms is one-fourth of the next 5 terms. Show that 20th term is - 112

Answer :

given an AP whose first term is 2

To find: 20th term of an AP

It is given that the sum of the first five terms is one-fourth of the next 5 terms


20a + 40d = 5a + 35d

15a + 5d = 0

Substituting a as 2

We get d = - 6

Hence 20th term is a + 19d = - 112

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