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Question: Answered & Verified by Expert
Let f:-1,3R  be defined as
fx=x+x,x+x,x+x,-1x<11x<22x3,
Where t denotes the greatest integer less than or equal to t. Then, f is discontinuous at:
MathematicsContinuity and DifferentiabilityJEE Main
Options:
  • A Only one point
  • B Only two points
  • C Four or more points
  • D Only three points
Solution:
2789 Upvotes Verified Answer
The correct answer is: Only three points

fx=x+x;-1x<1x+x;1x<2x+x;2x3

=-x-1;-1x<0x+0;0x<12x;1x<2x+2;2x<36;x=3           

At x=0, 1, 2, 3 f changes its definition.

 At x=0 LHL=-1, RHL=0f  is discontinuous at

x=0

x=1 LHL=1, RHL=2f is discontinuous at x=1

x=2 LHL=RHL=f2=4f is continuous at x=2

x=3 LHL=5, f3=6f is discontinuous at x=1

Points of discontinuity are 0, 1, 3.

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