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NDA Mathematics Hyperbola 2025 NDA 2025 (Phase 1)

NDA Mathematics Question (2025) — Solution

Question

What is the distance between the two foci of the hyperbola 25x^2 - 75y^2 = 225?

Options

  1. A. 2 3 units
  2. B. 4 3 units
  3. C. 6 units
  4. D. 2 6 units

Answer

B. 4 3 units

Step-by-step solution

The given equation of the hyperbola is 25x^2 - 75y^2 = 225. Dividing the entire equation by 225, we get: x^2 9 - y^2 3 = 1 Comparing this with the standard equation of a hyperbola x^2 a^2 - y^2 b^2 = 1, we have a^2 = 9 and b^2 = 3. The relation between a, b, and the distance from the center to a focus c is given by c^2 = a^2 + b^2. Substituting the values, we get: c^2 = 9 + 3 = 12 c = 12 = 2 3 The distance between the two foci is 2c. Distance = 2(2 3 ) = 4 3 units. Answer: 4 3 units

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