carilah suku ke 10,50,75,15,13 dari barisan 1,4,7,10,..

a = 1
b = 3
Un = a + b(n-1) = 1 +3n-3 = 3n-2
U10 = 3n - 2 = 3.10 -2 = 30 - 2 = 28
U50 = 3n - 2 = 3.50-2=150-2=148
U75 = 3n-2 = 3.75-2 = 225-2 = 223
U15 = 3n-2 = 3.15-2 = 45-2 = 43
U13 = 3n-2 = 3.13-2 = 39-2 = 37

un=a+(n-1)b)
u10=1+9.3
      =28
u50=1+49.3
       =148
u75=1+74.3
      =223u
u15=1+14.3
     =43
u13=1+12.3
     =37


ini barisan aritmatika!!!