Question

1+3+5+7+9+....+99 ( tanpa menghitung satu persatu

Answer 1

a = U1 = 1
b = U2 - U1 → 2

Un = a + (n-1)b
99 = 1 + (n-1)2
99 = 1 + 2n - 2
99 = 2n - 1
2n = 100
n = 100/2
n = 50

Sn = (n/2)(a + Un)
S50 = (50/2)(a + U50)
S50 = 25(1+99)
S50 = 25(100)
S50 = 2500