JEE Main 2018MathematicsSequences and SeriesEasyMCQ

JEE Main 2018 — Sequences and Series Question with Solution

JEE Main 2018 (15 Apr)

Question

If b is the first term of an infinite geometric progression whose sum is five, then b lies in the interval 

Choose an option

Show full solutionCorrect option: D
Correct answer
D0, 10

Step-by-step explanation

If b is the first term and r is the common ratio of an infinite G.P. and sum is 5, then

5=b1-r

⇒1-r=b5

⇒r=1-b5

⇒r=5-b5

∴-1<r<1

∴-1<5-b5<1

⇒-5<5-b<5

⇒-10<-b<0

⇒0<b<10

⇒b∈0, 10

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About this question

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.