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The set of points where the function f given by f(x) = |2x − 1| sinx is differentiable is ______. - Mathematics

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प्रश्न

The set of points where the function f given by f(x) = |2x − 1| sinx is differentiable is ______.

विकल्प

  • R

  • `"R" - {1/2}`

  • `(0, oo)`

  • None of these

MCQ
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उत्तर

The set of points where the function f given by f(x) = |2x − 1| sinx is differentiable is `"R" - {1/2}`.

Explanation:

Given that: f(x) = |2x − 1| sinx

Clearly, f(x) is not differentiable at x = `1/2`

R.H.L. = `"f'"(1/2) =  lim_("h" -> 0) ("f"(1/2 + "h") - "f"(1/2))/"h"`

= `lim_("h" -> 0) (|2(1/2 + "h") - 1|sin(1/2 + "h") - 0)/"h"`

= `lim_("h" -> 0) (|2"h"| sin((1 + 2"h")/2))/"h"`

= `2 sin (1/2)`

Also L.H.L. = `"f'"(1/2) =  lim_("h" -> 0) ("f"(1/2 - "h") - "f"(1/2))/(-"h")`

= `lim_("h" -> 0) (|2(1/2 - "h") - 1|[- sin (1/2 - "h")] - 0)/(-"h")`

= `(|-2"h"|[-sin(1/2 - "h")])/(-"h")`

= `- 2 sin (1/2)`

∴ R.H.L. = `"f'"(1/2)` ≠ L.H.L. `"f'"(1/2)`

So, the given function f(x) is not differentiable at x = `1/2`.

∴ f(x) is differentiable in `"R" - {1/2}`

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अध्याय 5: Continuity And Differentiability - Exercise [पृष्ठ ११३]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 12
अध्याय 5 Continuity And Differentiability
Exercise | Q 85 | पृष्ठ ११३

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