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Select the correct answer from the given alternatives : If f(x) = (4+5x4-7)4x, for x ≠ 0 and f(0) = k, is continuous at x = 0, then k is

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प्रश्न

Select the correct answer from the given alternatives:

If f(x) = `((4 + 5x)/(4 - 7x))^(4/x)`, for x ≠ 0 and f(0) = k, is continuous at x = 0, then k is

विकल्प

  • e7 

  • e3 

  • e12 

  • `"e"^(3/4)`

MCQ
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उत्तर

e12 

Explanation;

f(x) is continuous at x = 0

∴ f(0) = `lim_(x -> 0) "f"(x)`

= `lim_(x -> 0) ((4 + 5x)/(4 - 7x))^(4/x)`

= `lim_(x -> 0) [(4(1 + (5x)/4))/(4(1 - (7x)/4))]^(4/x)`

= `(lim_(x -> 0) [(1 + (5x)/4)^(4/(5x))]^5)/(lim_(x -> 0)[(1 - (7x)/4)^((-4)/(7x))]^(-7))`

= `"e"^5/"e"^(-7)  ...[(because x -> 0","  (5x)/4 -> 0","  (-7x)/4 -> 0),("and" lim_(x -> 0) (1 + x)^(1/x) = "e")]`

= e12

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अध्याय 8: Continuity - MISCELLANEOUS EXERCISE-8 [पृष्ठ १७७]

APPEARS IN

बालभारती Mathematics and Statistics (Arts and Science) Part 2 [English] Standard 11 Maharashtra State Board
अध्याय 8 Continuity
MISCELLANEOUS EXERCISE-8 | Q (I) (9) | पृष्ठ १७७

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