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Class 12 Differential Equations · Short Answer2 Marksseparable_differential_equations

Class 12 Maths · Differential Equations · Short Answer #94

Given y′ = e^(−2y) and y(5) = 0, find x when y = 3.

✅ Step-by-Step Solution

Final Answer: x = (e⁶ + 9)/2.
  1. Separate e^(2y)dy = dx.
  2. Integrate e^(2y)/2 = x + C. At (5, 0), C = −9/2, hence e^(2y) = 2x − 9.
  3. At y = 3, x = (e⁶ + 9)/2; the solution domain is x > 9/2.

📋 CBSE Stepwise Marking Scheme

  • [0.5 marks] Separate e^(2y)dy = dx.
  • [1 mark] Integrate e^(2y)/2 = x + C. At (5, 0), C = −9/2, hence e^(2y) = 2x − 9.
  • [0.5 marks] At y = 3, x = (e⁶ + 9)/2; the solution domain is x > 9/2.

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