tolong dibantu pake cara ya sob...mksh

→ p = 3x
→ l = x + 4

L = p x l
3x (x + 4) = 180cm²
3x² + 12x = 180
x² + 4x = 60
x² + 4x - 60 = 0
(x + 10)(x - 6) = 0
x = -10 atau x = 6

x = -10 → (TM, karena pnjang sisi tidak min)
maka, x = 6

→ p = 3x = 3 (6) = 18
→ l = x + 4 = 6 + 4 = 10

K = 2 (p + l)
K = 2 (18 + 10)
K = 2 (28)
K = 56 cm