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Find all points of discontinuity of f, where f is defined by: f(x) = {๐‘ฅ/|๐‘ฅ|, if ๐‘ฅ < 0, โˆ’1, if ๐‘ฅ โ‰ฅ 0 - Mathematics

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Question

Find all points of discontinuity of f, where f is defined by:

f(x) = `{(x/|x|", if"  x<0),(-1", if"  x >= 0):}`

Sum
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Solution

f(x) = `{(x/|x|", if"  x<0),(-1", if"  x >= 0):}`

`lim_(x -> 0^-)` f(x) = `lim_(x -> 0^-) x/abs x`

= `lim_(x -> 0^-) x/(-x)`

= `lim_(x -> 0^-)` (−1)

= −1

`lim_(x -> 0^+)` f(x) = `lim_(x -> 0^+)` (−1) = −1

Also f(0) = −1

Thus, `lim_(x -> 0^-)` f(x) = `lim_(x -> 0^+)` f(x) = f(0)

Hence, f is continuous at x = 0.

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

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NCERT Mathematics Part 1 and 2 [English] Class 12
Chapter 5 Continuity and Differentiability
Exercise 5.1 | Q 9 | Page 159

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