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JEE Main20211 Sep 2021Evening ShiftMathematicsContinuity and DifferentiabilityActual

Let [ t ] denote the greatest integer ≤ t . The number of points where the function f ( x ) = [ x ] x 2 - 1 + sin π [ x ] + 3 - [ x + 1 ] , x ∈ ( - 2 , 2 ) is not continuous is _____ .

Correct answer

0

Step-by-step solution

As [ . ] is discontinuous at integers so we will check at x = - 1 ,   0 ,   1 only at x = - 1 [ - 1 - ] = - 2 and [ - 1 + ] = - 1 we have LHL = ( - 2 ) · ( 0 ) + sin π + 1 = 1 RHL = ( - 1 ) · ( 0 ) + sin π 2 - 0 = 1 f ( - 1 ) = 1 ⇒ Continuous at x = - 1 Again at x = 0 [ 0 - ] = - 1   &   [ 0 + ] = 0 LHL = ( - 1 ) · ( 1 ) + sin π 2 - 0 = 0 RHL = 0 + sin π 3 - 1 ≠ LHL Hence, discontinuous at x   =   0 Again at x = 1 , [ 1 - ] = 0  

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