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NDA Mathematics Quadratic Equation 2026 NDA 2026 (Phase 1)

NDA Mathematics Question (2026) — Solution

Question

For a given k, what is the minimum value of x^2+kx+k^2 ?

Options

  1. A. 0
  2. B. k^2 4
  3. C. 3k^2 4
  4. D. k^2 2

Answer

C. 3k^2 4

Step-by-step solution

Let the given expression be f(x) = x^2 + kx + k^2. To find the minimum value, we can complete the square for the quadratic expression in x: f(x) = x^2 + kx + k^2 4 - k^2 4 + k^2 f(x) = (x + k 2 )^2 + 3k^2 4 Since the square of a real number is always non-negative, (x + k 2 )^2 0 for all real x. The minimum value of f(x) occurs when x = - k 2 . Therefore, the minimum value of the expression is 3k^2 4 . Answer: 3k^2 4

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