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MHT CET20192 May 2019Morning ShiftMathematicsApplication of DerivativesActual

If f x = 3 x 3 - 9 x 2 - 27 x + 15 , then the maximum value of f x is ________

Options

  1. A- 66
  2. B30
  3. C- 30
  4. D66

Correct answer

B. 30

Step-by-step solution

If f ( x ) = 3 x 3 - 9 x 2 - 27 x + 15 f ' x = 9 x 2 - 2 x - 3 = 9 x - 3 x + 1 f x maximum at x = - 1 ⇒ f - 1 = - 3 - 9 + 27 + 15 = 30

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