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Find all points of discontinuity of f, where f is defined by f(x)={x|x|ifx<0-1ifx≥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

Solution

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

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

= `lim_(h -> 0) ((0 - h))/ abs (0 - h)`

`= lim_(h -> 0) (-h)/h = - 1`

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

f(0) = - 1

Hence, f is continuous at x = 0.

There are no points of discontinuity here.

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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 9 | Page 159

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