1.sebuah persegi panjang mempunyai ukuran lebar (3x-5)cm dan panjang (x + 8)cm.apa bila keliling persegi panjang tersebut 54 cm,hitung luas persegi panjang ters

K = 2 × (p + l)
54 = 2 × (x + 8 + 3x - 5)
54 = 2 × (4x + 3)
54 = 8x + 6
8x = 54 - 6
8x = 48
x = 6

p = x + 8 = 6 + 8 = 14
l = 3x - 5 = 3(6) - 5 = 18 - 5 = 13

L = p × l
= 14 × 13
= 182 cm²

Keliling persegi panjang

Keliling = 2(p + l)

54 cm = 2(x + 8 + 3x - 5)

54 cm = 2(4x + 3)

54 cm = 8x + 6

54 cm - 6 = 8x

48 cm = 8x

48 ÷ 8 = x

6 = x

Panjang
= x + 8
= 6 + 8
= 14 cm

Lebar
= 3x - 5
= 18 - 5
= 13 cm

Luas persegi panjang

= p x l
= 14 cm x 13 cm
= 182 cm²
=