Question

Sebuah persegi panjang berukuran panjang (5x-1) cm dan lebar (2x+2) cm. jika keliling persegi panjang itu 72 cm, maka panjang dan lebarnya adalah

Answer 1

K = 2(p+l)
72 = 2[(5x-1)+(2x+2)]
72 = 10x-2+ 4x +4
72 -2 = 14x
70 = 14x
x = 5

panjang = 5x -1
= 5×5-1
=24cm
lebar = 2x+2
= 2×5+2
= 12cm

Answer 2

2 (panjang + lebar) = 72
2 {(5x-1)+(2x+2)} = 72
2 {5x+2x-1+2} = 72
2 {7x+1} = 72
14x + 2 = 72
14x = 72 -2
14x = 70
x = 70:14
x = 5

Panjang = 5x-1
               5.5 - 1 =25-1 =24 cm
Lebar= 2x+2
           2.5 +2 = 10+2 =12 cm