Matematika

Pertanyaan

carilah xn dari deret aritmatika 18+16+14...........jika n = 22

1 Jawaban

  • mungkin maksudnya Sn...?

    a = 18
    b = 16 - 18 = -2

    Sn = n/2(2a + (n-1)b)
    S22 = 22/2 (2 . 18 + (22 - 1)(-2))
    S22 = 11 (36 + (21 x (-2))
    S22 = 11 (36 + (-42))
    S22 = 11 (36 - 42)
    S22 = 11 x -6
    S22 = -66

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