Jawabanmu

2014-08-11T17:56:59+07:00
Dik : K = 72cm
s = 5x-7
dit : L?
Jb : K = 4s
72 = 4 (5x-7)
72 = 20x - 28
72 + 28 = 20x
100 = 20x
x = 100/20
x = 5cm

L = s . s
= 5cm.5cm
=25 cm^2
2014-08-11T18:00:38+07:00
Kll=72cm
sisi=72:4=18
5x-7=18
5x=18+7
x=5

jadi luas persegi=18x18 = 324 cm²