Question

Persegi panjang, panjang 3x cm, sedangkan lebarnya (x+6) cm, jika luasnya 120 cm2, maka kelilingnya?

Answer 1

Luas = p.l
120 = 3x * (x+6)
120 = 3x² + 18x
40 = x² + 6x
x² + 6 - 40 = 0
(x + 10)(x - 4) = 0
x = -10 (TM)
x = 4
keliling = 2 (p + l)
K = 2 (3x + x + 6)
K = 2 ( 4x + 6)
K = 2(16+6)
K = 44 cm

Semoga membantu :D
sorry kalo salah ato kurang jelas~

Answer 2

P x L = Luas
3x (x+6) = 120
3x² + 18x -120 = 0
x² + 6x - 40 = 0
(x + 10) ( x - 4) = 0
x= -10 atau x = 4
ambil Positif x = 4
P= 3x = 12cm
L= x+6= 10

Kliling= 2(p+L)
         = 2(12+10) = 2 (22) = 44cm