Matematika

Pertanyaan

Tolong dong bantu nomer 11, 12, 13
Tolong dong bantu nomer 11, 12, 13

1 Jawaban

  • 11.  Perkalian matrik
    5x + 2y = 16...(kalikan 2)
    2x + 3y = 2.....(kalikan 5)
    .
    10x  +4y = 32
    10x + 15y = 10
    kurangkan
    -11y = 22
    y = - 2
    2x + 3y = 2
    2x = 2 - 3y
    2x = 2 - 3(-2) =8
    x = 4
    xy = (4)(-2) = - 8

    12.
    a tegak lurus a ? salah soal
    a.a = 0
    (x,2, -4). (x,2,-4)= 0
    x² + 2(2) +(-4)(-4) =0
    x² + 4 + 16 = 0
    x² = -20 --> x = (tidak dapat ditentukan)

    13.
    cos∠ (a,b) = a.b / |a||b|
    a.b = 9(3) + (-3)(5) + 6(-2)= 27 -15 -12 = 0
    krn a.b = 0 --> maka cos <(a,b)= 0 = cos 90
    <(a,b) = 90°