Question

Suatu persegi panjang,panjangnya 5x-3 dan lebarnya 2x+2. jika kelilingnya 40m. berapa luasnya?

Answer 1

2(5x-3+2x+2) = 40
7x-1 = 20
x = 3

p=5x-3=5.3-3 =15-3 = 12
l=2x+2=2.3+2 = 6+2 =8

L = p.l = 12.8 = 96 m^2

Answer 2

Dikethui :
p = 5x-3
l = 2x + 2
K = 40
mka :
K = 2 x (p+l)
40 = 2 x [5x-3 + 2x + 2]
40 = 2 x (7x -1)
40 = 14x - 2
42 = 14 x
x = 42/14
x = 3

jadi :
p = 5x-3 = 5(3) - 3 = 12
l = 2x + 2 = 2 (3) + 2 = 8

Luas = p x l
          = 12 x 8
          = 96 m²