JEE Main 2018 — Sequences And Series Question with Solution
From: JEE Main 2018 (Online) 15th April Morning Slot
Question
If b is the first term of an infinite G.P. whose sum is five, then b lies in the interval :
Choose an option
Show full solutionCorrect option: C
Correct answer
C(0, 10)
Step-by-step explanation
Sum of infinite G.P,
S = where
5 =
1 - r =
b = 5(1 - r)
as
-1 < r < 1
1 > -r > -1
2 > 1-r > 0
10 > 5(1-r) > 0
10 > b > 0
interval of b = (0, 10)
S = where
5 =
1 - r =
b = 5(1 - r)
as
-1 < r < 1
1 > -r > -1
2 > 1-r > 0
10 > 5(1-r) > 0
10 > b > 0
interval of b = (0, 10)
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This is a previous-year question from JEE Main 2018, covering the Sequences And Series chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.