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


So


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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