Matematika

Pertanyaan

Materi Persamaan Kuadrat,
untuk rumus
x₁² + x₂² = (x₁ + x₂)² – 2x₁x₂
kalau x₁² – x₂² = ...?
Beserta pembuktiannya.

2 Jawaban

  • ( x₁ + x₂ )( x₁ - x₂ ) = x₁² - x₁x₂ + x₁x₂ - x₂²
    ( x₁ + x₂ )( x₁ - x₂ ) = x₁² - x₂²
  • jawab

    x₁² + x₂² = ( x₁ + x₂)²  - 2 x₁ x₂
    x₁² - x₂² = (x₁ + x₂) (x₁ - x₂)
    = √(x₁ + x₂)² (x₁ - x₂)²
    = √(x₁² + x₂² + 2x₁x₂)(x₁² + x₂² - 2x₁ x₂)
    = √(x₁⁴ + x₂⁴ - 2(x₁ x₂)²
    = √{(x₁² + x₂²)² - 4(x₁ x₂)²}
    = √{(x₁ + x₂)² - 2(x₁ x₂)}² - 4(x₁ x₂)²
    = √{(x₁ + x₂)⁴ - 4(x₁+x₂)²(x₁ x₂) + 4(x₁ x₂)² - 4(x₁x₂)²
    = √{x₁ + x₂)⁴ - 4(x₁+x₂)²(x₁ x₂)}

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