JEE Main 2017MathematicsFunctionsMediumMCQ

JEE Main 2017 — Functions Question with Solution

JEE Main 2017 (08 Apr Online)

Question

Let fx=210x+1 and gx=310x-1. If fogx=x, then x is equal to:

Choose an option

Show full solutionCorrect option: B
Correct answer
B1-2-10310-2-10

Step-by-step explanation

Given fgx=x

Where,fx=210x+1 ,gx=310x-1.

⇒f310x-1=210310x-1+1

⇒210310x-1+1=x

⇒x610-1=210-1

⇒x=210-1610-1=210-1210(2×3)10-1210

=1-2-10310-2-10

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About this question

This is a previous-year question from JEE Main 2017, 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.