Progression (Sequence and Series)Hard
Question
Consider an infinite geometric series with first terma and common ratio r, If its sum is 4 and the second term is 3 /4, then
Options
A.a = 4 / 7, r = 3 / 7
B.a = 2, r = 3 / 8
C.a = 3 / 2, r = 1/ 2
D.a = 3, r =1/ 4
Solution
Since, sum = 4 and second term = 
It is given first terma and common ratio r.
⇒
= 4, ar = 
⇒
⇒
⇒
⇒ (a - 1)(a - 3) = 0
⇒ a = 1 of 3
When a = 1, r = 3 / 4 and when a = 3, r = 1 / 4
Therefore, (d) is the answer.
It is given first terma and common ratio r.
⇒
= 4, ar = ⇒
⇒
⇒
⇒ (a - 1)(a - 3) = 0
⇒ a = 1 of 3
When a = 1, r = 3 / 4 and when a = 3, r = 1 / 4
Therefore, (d) is the answer.
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