1. keliling sebuah kebun yang berbentuk persegi panjang adalah 70 m . jika luas kebun tersebut adalah 300mkuadrat, berapakah panjang diagonal kebun tersebut!

1. K  = 70
   2(p+l) = 70
   p+l = 35
     p = 35-l

    L = 300
   p.l = 300
  (35-l)l = 300
  35l – l^2 = 300
-l² + 35l -300 = 0
l² – 35l +300 = 0
(l-15) (l-20) = 0
l =15 atau 20
jika l =15 ,maka p = 35 – l = 35 – 15 = 20
jika l=20 ,maka p = 35-l = 35-20 = 15
jadi
   diagonal = √ 15²+20² = √225+400 = √625 = 25 cm
2. K = K =   = 90
   2(p+l) = 90
   p+l = 45
     p = 45-l

    L = 450
   p.l = 450
  (45-l)l = 450
  45l – l^2 = 450
-l² + 45l -450 = 0
l² – 45l + 450 = 0
(l-30) (l-15) = 0
l =15 atau 30
jika l = 15 ,maka p = 45 – l = 45 – 15 = 30
jika l=30 ,maka p = 45-l = 45-30 = 15

1. 70m = 2p + 2l
2(p+l) = 70
p+l = 35 – > p = 35-l
pl = 300
(35-l)l = 300
35l – l^2 = 300
-l^2 + 35l -300 = 0
l^2 – 35l +300 = 0
(l-15) (l-20) = 0
l =15,20
jika l =15 ,maka
p = 20
jika l=20 ,maka
p=15
maka :
jika l =15 dan p =20
diagonal =25 m
jika l =20 dan p=15
diagonal =25 m
2.2(p+l) = 90 -> p+l = 45 -> p =45-l
   pl =450
   (45-l)l=450
    45l – l^2 -450 = 0
    l^2-45l+450 = 0
    (l-30) (l-15) =0
     l =30,15
     jika lebar =30 ,maka p=45-30 =15m
     jika lebar = 15 ,maka p =45-15 =30m