Matematika

Pertanyaan

Jika x1 dan x2 adalah akar-akar persamaan kuadrat 8x2 - 53x - 21 = 0, maka nilai x12 + x22 adalah

2 Jawaban

  • Kelas 10 Matematika
    Bab Persamaan Kuadrat

    8x² - 53x - 21 = 0
    a = 8; b = -53; c = -21

    (x1)² + (x2)²
    = (x1 + x2)² - 2 . x1 . x2
    = (-b/a)² - 2 . c/a
    = (- (-53)/8)² - 2 . (-21/8)
    =  2.809/64 + 42/8
    = 2.809/64 + 336/64
    = 3.145/64
    = 49  9/64
  • 8x² - 53x - 21 = 0
    a = 8; b = -53; c = -21

    (x1)² + (x2)²
    = (x1 + x2)² - 2 . x1 . x2
    = (-b/a)² - 2 . c/a
    = (- (-53)/8)² - 2 . (-21/8)
    =  2.809/64 + 42/8
    = 2.809/64 + 336/64
    = 3.145/64
    = 49  9/64

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