tolong dijawab ya guys

Mapel : Matematika
Bab : Barisan dan Deret

Barisan Aritmatika

Un = bn + a - b
U4 = 4b + a - b
 14 = 3b + a

Un = bn + a - b
U8 = 8b + a - b
 26 = 7b + a

14 = 3b + a
26 = 7b + a
----------------  -
-12 = -4b
   b = -12/-4
   b = 3

14 = 3b + a
14 = 3(3) + a
14 = 9 + a
  a = 14 - 9
  a = 5

  Un = bn + a - b
U20 = 3(20) + 5 - 3
U20 = 60 + 2
U20 = 62

Un=a+(n-1) b
U4=a+(3xb) =14
U8=a+(7xb) =26
_________ _
-4b=-12
b=3
U4=a+9=14
a=5
U20=a+(n-1) b=5+(19x3) =5+57=62
semoga membantu
insya allah benar