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Class 12 Applications Of Derivatives · Short Answer2 Marksmonotonicity

Class 12 Maths · Applications Of Derivatives · Short Answer #41

Find the maximal intervals on which y=[x(x−2)]² is strictly increasing.
Derivative sign chart (vsa 4)
Derivative sign chart (vsa 4)

✅ Step-by-Step Solution

Final Answer: [0,1] and [2,∞)
  1. y′=4x(x−1)(x−2), with zeros 0,1,2.
  2. The derivative is positive on (0,1) and (2,∞), negative on the remaining open intervals. Strict increase extends to finite endpoints.
  3. Thus the maximal intervals are [0,1] and [2,∞).

📋 CBSE Stepwise Marking Scheme

  • [0.5 marks] y′=4x(x−1)(x−2), with zeros 0,1,2.
  • [1 mark] The derivative is positive on (0,1) and (2,∞), negative on the remaining open intervals. Strict increase extends to finite endpoints.
  • [0.5 marks] Thus the maximal intervals are [0,1] and [2,∞).

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