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Examine the continuity of f, where f is defined by ,f(x)={sinx-cosxifx≠0-1,ifx=0 - Mathematics

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प्रश्न

Examine the continuity of f, where f is defined by `f(x) = {(sin x - cos x, if x != 0),(-1, "," if x = 0):}`

योग

उत्तर

`"f"("x") = {("sin x" - "cos x""," " if"  "x" ne 0),(-1"," " if" "x" = 0):}`

Approach1:

If f(x) is continuous at x = c, it implies:

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

`=> -1 = sin 0 - cos 0 = -sin 0 - cos 0`

`=> -1 = -1 = -1`

Which is true, i.e. f(x) is continuous at x = 0.

Approach2:

`c ne 0  and  c sub R`

If f(x) is continuous at x = c, it implies:

sin c - cos c is continuous, i.e. sin c and cos c are continuous functions, which is true.

That is, f(x) is also continuous at `x ne 0`.

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अध्याय 5: Continuity and Differentiability - Exercise 5.1 [पृष्ठ १६१]

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एनसीईआरटी Mathematics [English] Class 12
अध्याय 5 Continuity and Differentiability
Exercise 5.1 | Q 25 | पृष्ठ १६१

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