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NDA Mathematics Trigonometric Equations 2026 NDA 2026 (Phase 1)

NDA Mathematics Question (2026) — Solution

Question

What is the smallest positive x satisfying _ x x+ _ x x=2 ?

Options

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

Answer

C. 4

Step-by-step solution

Let t = _ x x. The given equation becomes t + 1 t = 2. t^2 - 2t + 1 = 0 (t - 1)^2 = 0 t = 1 _ x x = 1 x = x x = 1 The smallest positive value of x is 4 . For x = 4 , x = 1 2 and x = 1 2 , which satisfy the conditions for the base and argument of logarithms (positive and not equal to 1). Answer: 4

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