Matematika

Pertanyaan

diketahui barisan aritmatika U3=3, U4+U6=14. Tentukan S6

1 Jawaban

  • BaRisan AritMatiKa

    U3 = 3
    a + 2b = 3 ... (1)

    U4 + U6 = 14
    2a + 8b = 14
    a + 4b = 7 ... (2)

    (1) - (2) = 3 - 7
    2b - 4b = -4
    -2b = -4
    b = 2

    a + 2b = 3
    a = 3 - 2b
    a = -1

    Sn = n/2 (2a + (n - 1)b)

    S6 = 6/2 (-2 + 5(2))
    S6 = 3 × 8
    S6 = 24

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