Question

Hitung jumlah bilangan kelipatan 5 dari 50 sampai dengan 100

Answer 1

Verified answer

50 + 55 + 60 + 65 + ... + 100

A = 50
B = 5
Banyak suku :
= 100 : 5 : 2 + 1
= 20 : 2 + 1
= 11

S11 :
= n/2 (a + Un)
= 11/2 (50 + 100)
= 5,5 x 150
= 825

Answer 2

Verified answer

Un = a + (n-1) b
 100 = 50 + (n - 1) 5
100 = 50 + 5n -5
5n = 100 - 45
n = 55:5 = 11

Sn = n/2 (a+un)
=11/2 (50+100)
=11/2 (150)
=1650/2
=825