Question

Panjang Dan lebar suatu persegi panjang adalah (x + 3) cm Dan (x- 2) cm. bila kelilingnya 30 cm mama luas persegi ITU adalah.?

Answer 1

Dik :
panjang = x+3
lebar = x - 2
K = 30

maka :
K = 2 x (p + l)
30 = 2 x (x + 3 + x -2)
30 = 2 x (2x + 1)
30 = 4x + 2
4x = 30-2
x  = 28/4
x = 7 cm

jadi :
panjang = 7+3 = 10 cm
lebar = 7-2 = 5 cm

maka :
L = 10 x 5 = 50 cm²

Answer 2

K = 2(p+l)
30 = 2 ((x+3)+(x-2))
30 = 2x+6+2x-4
30 = 4x +2
30-2 = 4x
28 = 4x
x=4

L = p×l
= (x+3) ×(x-2)
= (4+3) × (4-2)
= 7 × 2
= 14 cm kuadrat.