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Question: Answered & Verified by Expert
The function fx=limncos2nπx+x is (where, . denotes the greatest integer function and nN)
MathematicsContinuity and DifferentiabilityJEE Main
Options:
  • A continuous at x=1 but discontinuous at x=32
  • B continuous at x=1 and x=32
  • C discontinuous at x=1 and x=32
  • D discontinuous at x=1 but continuous at x=32
Solution:
2601 Upvotes Verified Answer
The correct answer is: discontinuous at x=1 but continuous at x=32

fx=limncos2πxn+x

=x:cos2πx0,11+x:cos2πx=1
=x:xΙ1+x:xΙ
For x=1,
f1-=1-=0, f1+=1+=1, f1=1+1=2
f1+f1-fx is discontinuous at x=1
For x=32,

f32+=32+=1, f32-=32-=1, f32=32=1
f32-=f32+=f32
fx is continuous at x=32

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