diketahui barisan 2,5,8,11...suku ke_100 adalah

Suku ??
a = 2
b = U2 - U1 = 5 - 2 = 3
Sn = n/2 (2a + (n-1) × b)
S100 = 100/2 (2(2) + (100-1) × 3)
S100 = 50 (4 + (99) × 3
S100 = 50 (4 + 297)
S100 = 50 (301)
S100 = 15.050

Urutan Kali Bukan Suku !
Un = a + (n-1) × b
U100 = 2 + (100-1) × 3
U100 = 2+(99)×3
U 100 = 2+297 = 299

b
= u2 - u1
= 5 - 2
= 3

U100 =  a + 99b
U100 = 2 + 99(3)
          = 2 + 297
          = 299