Question

Tolong dong bantu nomer 11, 12, 13

Answer 1

Verified answer

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°