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Class 12 Applications Of Derivatives · Short Answer2 Marksrelated_rates

Class 12 Maths · Applications Of Derivatives · Short Answer #43

A particle moves on 3y=ax³+1. At x=1 its signed y-rate is twice its nonzero signed x-rate. Find a.

✅ Step-by-Step Solution

Final Answer: a=2
  1. Differentiate in time: 3ẏ=3ax²ẋ, hence ẏ=ax²ẋ.
  2. At x=1 use ẏ=2ẋ and ẋ≠0: 2ẋ=a ẋ.
  3. Therefore a=2.

📋 CBSE Stepwise Marking Scheme

  • [0.5 marks] Differentiate in time: 3ẏ=3ax²ẋ, hence ẏ=ax²ẋ.
  • [1 mark] At x=1 use ẏ=2ẋ and ẋ≠0: 2ẋ=a ẋ.
  • [0.5 marks] Therefore a=2.

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