Question

Tolong y buat di kumpulin esok hari

Answer 1

7. D
7x - 4y = 43 ... (1) (×3)
3x + 5y = 5 ... (2) (×7)
_________
21x - 12y = 129
21x + 35y = 35
____________ -
-47y = 94
y = -2

masukkan ke (1)
7x - 4 × (-2) = 43
7x + 8 = 43
7x = 35
x = 5

HP = {5, -2}


8. A
7x + 3y = 15 ... (1)
y = x - 3 ... (2)

masukkan (2) ke (1),
7x + 3(x - 3) = 15
7x + 3x - 9 = 15
10x = 24
x = 2 2/5

masukkan ke (2),
y = 2 2/5 - 3 = -3/5

HP = {2 2/5 , -3/5}


9. A
x - 2y = 3 ... (1)
5x - 2y = -1 ... (2)
_________ -
-4x = 4
x = -1

masukkan ke (1),
-1 - 2y = 3
-2y = 4
y = -2

HP = {-1 , -2}


10.


kalikan (1) dgn 20
kalikan (2) dgn 4,

5x + 8y = 20y + 40
2x + 3y = 4x + 28
______________
5x - 12y = 40 ... (1)'
-2x + 3y = 28 ... (2)' (×4)
______________
5x - 12y = 40
-8y + 12y = 112
______________ +
-3y = 152
y = -50 2/3

masukkan ke (2)'
-2x - 153 = 28
-2x = 181
x = -90 1/2