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If f(x) = m,ifn,If{mx+1, if x≤π2sinx+n, If x>π2, is continuous at x = π2, then ______. - Mathematics

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Question

If f(x) = `{{:("m"x + 1",",  "if"  x ≤ pi/2),(sin x + "n"",",  "If"  x > pi/2):}`, is continuous at x = `pi/2`, then ______.

Options

  • m = 1, n = 0

  • m = `("n"pi)/2 + 1`

  • n = `("m"pi)/2`

  • m = n = `pi/2`

MCQ
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Solution

If f(x) = `{{:("m"x + 1",",  "if"  x ≤ pi/2),(sin x + "n"",",  "If"  x > pi/2):}`, is continuous at x = `pi/2`, then n = `("m"pi)/2`.

Explanation:

Given that: f(x) = `{{:("m"x + 1",",  "if"  x ≤ pi/2),(sin x + "n"",",  "If"  x > pi/2):}`, is continuous at x = `pi/2`

L.H.L. = `lim_(x -> pi^-/2) ("m"x + 1)`

= `lim_("h" -> 0) ["m"(pi/2 - "h") + 1]`

= `("m"pi)/2 + 1`

R.H.L. = `lim_(x -> pi^+/2) (sinx + "n")`

= `lim_("h" -> 0) [sin(pi/2 + "h") + pi]`

= `lim_("h" -> 0) cos "h" + "n"`

= 1 + n

When f(x) is continuous  at x = `pi/2`

∴ L.H.L. = R.H.L.

`("m"pi)/2 + 1` = 1 + n

⇒ n = `("m"pi)/2`.

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

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NCERT Exemplar Mathematics [English] Class 12
Chapter 5 Continuity And Differentiability
Exercise | Q 89 | Page 114

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