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
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