hasil dari 105+101+97+...5+1 adalah

Bab Barisan dan Deret
Matematika SMP Kelas IX

105 + 101 + 97 + .... + 1 = ?

a = 105

b = U2 - U1
b = 101 - 105
b = -4

Un = a + (n - 1) x b = 1
105 + (n - 1) x (-4) = 1
(n - 1) x (-4) = 1 - 105
n - 1 = -104/-4
n = 26 + 1
n = 27

Sn = (n/2) x (a + Un)
S27 = (27/2) x (105 + 1)
S27 = (27/2) x 106
S27 = 1.431