Question

Sebuah balok dengan perbandingan p:l:t=5:2:1 mempunyai luas permukaan 306cm².volume balok tersebut adalah

Answer 1

306 = 2(p x l) + 2(p x t) + 2(l x t)
306 = 2(5y x 2y) + 2(5y x y) + 2(2y x y)
306 = 2 (10y²) + 2(5y²) + 2(2y²)
306 = 20y² + 10y² + 4y²
306 = 34y²
306 : 34 = y²
9 = y²
√9 = y
3 = y


p = 5y = 5 x 3 = 15 cm
l = 2y = 2 x 3 = 6 cm
t = y = 3 cm

V = p x l x t
V = 15 x 6 x 3
V = 270 cm³

Answer 2

Lp =(2 x p x l ) + ( 2 x p x t ) + ( 2 x l x t )
306=(2 x 5a x 2a) + (2 x 5a x a) + (2 x 2a x a)
306 = 20a² + 10a² + 4a²
306 = 34a²
a² = 9
a = 3

p = 5a = 5(3) = 15 cm
l = 2a = 2(3) = 6 cm
t = a = 3 cm

Maka;
V = p x l x t = 15 x 6 x 3 = 270 cm³