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Find the value of k so that the function f is continuous at the indicated point. f(x) = {๐‘˜โข๐‘ฅ + 1, if ๐‘ฅ โ‰ค ๐œ‹, cos โก๐‘ฅ, if ๐‘ฅ > ๐œ‹, at x = ฯ€

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Question

Find the value of k so that the function f is continuous at the indicated point.

f(x) = `{(kx +1", if"  x<= pi),(cos x", if"  x > pi):}` at x = π

Sum
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Solution

f(x) = `{(kx +1", if"  x<= pi),(cos x", if"  x > pi):}`

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

f(π) = `lim_(x -> pi^+)` f(x) = `lim_(x -> pi^-)` f(x)

⇒ k(π) + 1 = cos(π)

⇒ k(π) + 1 = −1

⇒ k(π) = −2

⇒ k = `(-2)/pi`

That is, for the quantity k = `(-2)/pi` this function is continuous at x = π.

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Chapter 5: Continuity and Differentiability - Exercise 5.1 [Page 161]

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NCERT Mathematics Part 1 and 2 [English] Class 12
Chapter 5 Continuity and Differentiability
Exercise 5.1 | Q 28 | Page 161

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