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Question: Answered & Verified by Expert
If f:RR is a function defined by f(x)=xsin2x-12π, where x denotes the greatest integer function, then f is
MathematicsContinuity and DifferentiabilityJEE Main
Options:
  • A continuous for every real x
  • B discontinuous only at x=0
  • C discontinuous only at integral values of x
  • D continuous only at x=0
Solution:
1640 Upvotes Verified Answer
The correct answer is: discontinuous only at integral values of x
Doubtful points are x=n, nΙ
L.H.L=limxn-xsin2x-12π
=n-1sin2n-12π=±n-1
R.H.L=limxn+xsin2x-12π
=nsin2n-12π=±n
fn=±n 
Clearly, LHL,RHL, fn all cannot be equal for any nΙ
Hence, discontinuous at all integeral values of x

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