Question

1. persegi panjang mempunyai panjang 2 kali lebarnya. Jika keliling persegi panjang 54 cm, maka luas persegi panjang tersebut adalah?


2. Fungsi f didefinisikan dengan rumus f(x)= px+q. Jika f(3)=-10 dan f(-2)=0, maka nilai f(-7) adalah

Answer 1

1)
p = 2l
maka,
K = 54
2(p+l) = 54
p+l = 54/2
p+l = 27
2l+l = 27
3l = 27
l = 27/3
l = 9 cm → p = 2l = 2.9 = 18 cm
jadi,
L = p.l = 18.9 = 162 cm²

Answer 2

1)
diket :
p = 2l
l = l
Kp = 54 cm

ditanya : Lp...?
jawab :

2(p+l) = Kp
2(2l + l) = Kp
2(3l) = Kp
6l = Kp
l = Kp/6
l = 54/6
l = 9 cm

p = 2(9) = 18 cm
l = 9 cm

• Lp = p × l
• Lp = 18 × 9
• Lp = 162 cm^2

2)
f(x) = px+q
f(3) = 3p + q = -10
f(-2) = -2p + q = 0
--------------------- -
••••• 5p = -10
••••• p = -2

f(3) = 3p + q = -10
•••• 3(-2) + q = -10
•••• -6 + q = -10
•••• q = -10+6
•••• q = -4

• f(-7) = -2x -4
• f(-7) = -2(-7) -4
• f(-7) = 14-4
• f(-7) = 10