Matematika

Pertanyaan

Tolong besok mau dikumpulkan 16 sampai 20
Tolong besok mau dikumpulkan 16 sampai 20

1 Jawaban

  • 16.
    3x² + 7x - 6 = 0
    3x² + 9x - 2x - 6 = 0
    3x(x + 3) - 2(x + 3) = 0
    (3x - 2)(x + 3) = 0

    3x - 2 = 0
    3x = 2
    x = 2/3

    dan

    x + 3 = 0
    x = -3

    HP = {-3, 2/3}
    Jawaban C

    17.
    5x² - 2x - 3 = 0
    5x² - 5x + 3x - 3 = 0
    5x(x - 1) + 3(x - 1) = 0
    (5x + 3)(x - 1) = 0

    5x + 3 = 0
    5x = -3
    x = -3/5

    dan
    x - 1 = 0
    x = 1

    Jawaban B

    18.
    misal
    bilangan bulat tsb adalah a dan b
    maka
    a + b = 3
    a = 3 - b

    a . b = -108
    (3 - b) . b = -108
    3b - b² = -108
    b² - 3b - 108 = 0
    (b + 9)(b - 12) = 0

    b + 9 = 0
    b = -9

    dan

    b - 12 = 0
    b = 12

    Jawaban C

    19.
    L = 396 m²
    l = p - 4

    L = p x l
    L = p x (p - 4)
    396 = p² - 4p
    p² - 4p - 396 = 0
    (p + 18)(p - 22) = 0

    p + 18 = 0
    p = -18 (tidak memenuhi, karena ukuran panjang tidak mungkin negaitf)

    p - 22 = 0
    p = 22

    l = p - 4
    l = 22 - 4
    l = 18

    maka
    panjang = 22 m
    lebar = 18 m

    Keliling = 2(p + l)
    K = 2(22 + 18)
    K = 2 x 40
    K = 80 m

    Jawaban C

    20.
    Luas = 180 m²
    P x L = 180

    Keliling = 54 m
    2(P + L) = 54
    P + L = 27
    p = 27 - L

    p x L = 180
    (27 - L) x L = 180
    27l - L² = 180
    L² - 27L + 180 = 0
    (L - 15)(L - 12) = 0

    L - 15 = 0
    L = 15

    atau

    L - 12 = 0
    L = 12

    karena ukuran lebar lebih pendek dari panjang, maka lebar taman adalah 12 m

    Jawaban D