JEE Main 2019 — Functions Question with Solution
From: JEE Main 2019 (Online) 11th January Morning Slot
Question
Let fk(x) = for k = 1, 2, 3, ... Then for all x R, the value of f4(x) f6(x) is equal to
Choose an option
Show full solutionCorrect option: D
Correct answer
D
Step-by-step explanation
f4(x) f6(x)
= (sin4 x + cos4 x) (sin6 x + cos6 x)
= (1 sin2 2x) (1 sin2 2x) =
= (sin4 x + cos4 x) (sin6 x + cos6 x)
= (1 sin2 2x) (1 sin2 2x) =
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This is a previous-year question from JEE Main 2019, covering the Functions 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.