Question

Jumlah bilangan ganjil dari 2 sampai dengan 30 adalah
a.183
b.203
c.373
d.380

Jawab guys! :D

Answer 1

3, 5, 7, 9,...,29 aritmatika

U1 = a = 3
U2 = 5
Beda = U2 - U1 = 5 - 3 = 2
Un = 29
a + (n - 1)b = 29
3 + (n - 1)2 = 29
3 + 2n - 2 = 29
2n + 1 = 29
2n = 29 - 1
2n = 28
n = 28/2
n = 14

Sn = n/2 (2a + (n - 1)b
S14 = 14/2 (2 . 3 + (14 - 1) . 2)
S14 = 7 (6 + 13 . 2)
S14 = 7 (6 + 26)
S14 = 7 . 32
S14 = 224


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