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Let f(x) = |sin x|. Then ______.

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Question

Let f(x) = |sin x|. Then ______.

Options

  • f is everywhere differentiable

  • f is everywhere continuous but not differentiable at x = nπ, n ∈ Z

  • f is everywhere continuous but not differentiable at x = `(2"n" + 1)  pi/2`, n ∈ Z

  • None of these

MCQ
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Solution

Let f(x) = |sin x|. Then f is everywhere continuous but not differentiable at x = nπ, n ∈ Z.

Explanation:

Given that: f(x) = |sin x|

Let g(x) = sin x and t(x) = |x|

∴ f(x) = tog(x) = t[g(x)] = t(sin x) = |sin x|

Where g(x) and t(x) both are continuous.

∴ f(x) = got(x) is continuous but t(x) is not differentiable at x = 0.

So, f(x) is not continuous at sin x = 0

⇒ x = nπ, n ∈ Z.

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Chapter 5: Continuity And Differentiability - Exercise [Page 114]

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NCERT Exemplar Mathematics Exemplar [English] Class 12
Chapter 5 Continuity And Differentiability
Exercise | Q 90 | Page 114

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