SOLUTION: The 5th term of an arithmetic progression is three times the first term.find the sum of the first eight terms of the progression given that a quarter of the fifth term is 9
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Question 870009: The 5th term of an arithmetic progression is three times the first term.find the sum of the first eight terms of the progression given that a quarter of the fifth term is 9 Answer by mananth(16946) (Show Source):
You can put this solution on YOUR website! The 5th term of an arithmetic progression is three times the first term.find the sum of the first eight terms of the progression given that a quarter of the fifth term is 9
let first term be a
and common difference be d
t5 = 3a
(1/4)t5 =9
t5=36
3a=36
a=12
t5=a+4d
36=12+4d
24=4d
6=d
a=12,d=6
Sn = (n/2) (2a+(n-1)d)
S8=(8/2)(2*12+(7*6))
=4*(14+13)
=(4*27)
=108
