390 = 30 + 15 ( n - 1 )
390 - 30 = 15 ( n - 1 )
360 = 15 ( n - 1 )
360 : 15 = n - 1
24 = n - 1
n = 24 + 1
Kemudian tentukan jumlah deret tersebut:
S25 = 25/2 ( 30 + 390 )
S25 = 12,5 ( 420 )
390 = 30 + 15 ( n - 1 )
390 - 30 = 15 ( n - 1 )
360 = 15 ( n - 1 )
360 : 15 = n - 1
24 = n - 1
n = 24 + 1
Kemudian tentukan jumlah deret tersebut:
S25 = 25/2 ( 30 + 390 )
S25 = 12,5 ( 420 )
Editor: Wahyu Pratama
Sumber: kemdikbud.go.id