JEE Main 2020MathematicsSequences and SeriesHardMCQ

JEE Main 2020 — Sequences and Series Question with Solution

JEE Main 2020 (04 Sep Shift 1)

Question

If 1+1-22·1+1-42·3+1-62·5+……+1-202·19=α-220 β, then an ordered pair α, β is equal to:

Choose an option

Show full solutionCorrect option: B
Correct answer
B(11, 103)

Step-by-step explanation

S=1+∑r=1101−2r22r−1

=1+10−∑r=1108r3−4r2

=11−810×1122−410×11×216

=11−21102−140×11

=11−221100−70

=11−220110−7

∴ α−220β=11−220103

∴ α=11, β=103

α, β=11, 103.

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About this question

This is a previous-year question from JEE Main 2020, 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.