Subject:  Algebra

Solve x² + 4 = 0

Solve a quadratic equation that has complex conjugate roots.

Answer x = 0 ± 2i

Solution

  1. Equation 1x² + 0x + 4 = 0
  2. Vertex (h, k) = (−b/2a, c − b²/4a) = (0, 4)
  3. Axis of symmetry x = 0
  4. Discriminant Δ = b² − 4ac = (0)² − 4·1·4 = -16
  5. Complex roots Δ < 0 → two complex conjugate roots
  6. x (−b ± √Δ) / 2a = 0 ± 2i

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