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Question 310011
JEE Mathematics · Hard

Application of Derivatives: Monotonicity MCQ

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MonotonicityHardQuestion 310011

Question

f(x) = 2x³ − 9x² + 12x − 5 is decreasing on:
  1. A
    (1, 2)
    Correct
  2. B
    (0, 1)
  3. C
    (2, ∞)
  4. D
    (−∞, 1)

Correct answer

(1, 2)

Explanation

f'(x) = 6x²−18x+12 = 6(x²−3x+2) = 6(x−1)(x−2). f'(x) < 0 when 1 < x < 2. So f is decreasing on (1, 2).

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