Question

Sebuah persegi panjang , panjangnya (3x +2)cm dan lebarnya (x-2)jika keliling persegi panjang tersebut 40 cm. Tentukan luas persegi panjang tersebut!

Answer 1

Panjang = 3x + 2
lebar = x - 2

keliling = 2 (p + l)
40 cm = 2(3x+2+x-2)
40 cm = 2(4x)
40 cm = 8x
x = 40/8
x = 5

maka
panjang = 3(5) + 2 = 17 cm
lebar = 5 - 2 = 3 cm

jadi Luasnya
L = p x l
L = 17 x 3
L = 51 cm²

Answer 2

K = p+l+p+l
40 = (3x+2) + (x-2) + (3x+2) + (x-2)
40 = 8x
x = 5

p = 3x + 2
p = 3(5) + 2
p = 15 + 2
p = 17cm

l = x-2
l = 5-2
l = 3cm

L = p x l
L = 17 x 3
L = 51cm^2