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Find all point of discontinuity of f, where f is defined by f(x)={2x+3ifx≤22x-3ifx>2 - Mathematics

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Question

Find all point of discontinuity of f, where f is defined by `f (x) = {(2x + 3, if x<=2),(2x - 3, if x > 2):}`

Sum

Solution

`f (x) = {(2x + 3, if x<=2),(2x - 3, if x > 2):}`

`lim_(x -> 2)` f(x) = `lim_("x" -> 2^-)` (2x + 3)

`= lim_(h -> 0) [2(2 - h) + 3]`

`= lim_(h -> 0) [4 - 2h + 3]`

`= lim_(h -> 0) (7 - 2h)`

`= 7 - 2 xx 0`

= 7

`lim_(x -> 2^+)` f(x) = `lim_(x -> 2^+)` (2x + 3)

`= lim_(h -> 0) [2(2 + h) - 3]`

`= lim_(h ->0) [4 + 2h - 3]`

`= lim_(h ->0) (1 + 2h)`

`= 1 + 2 xx 0`

= 1

Therefore, f is not continuous at x = 2.

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Chapter 5: Continuity and Differentiability - Exercise 5.1 [Page 159]

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NCERT Mathematics [English] Class 12
Chapter 5 Continuity and Differentiability
Exercise 5.1 | Q 6 | Page 159

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