Question

Cari jumlah 60 suku pertama pada tiap deret 1+3+5+7+...

Answer 1

A = 1
b = 3-1 = 2

Sn = n/2 (2a + (n-1)b)
S60 = 60/2 (2x1 + (60-1)2)
S60 = 30 ( 2 + ( 59 x 2)
S60 = 30 (2 + 118)
S60 = 30 (120)
S60 = 3600

Answer 2

A=1,b=2
lalu masukkan ke
Sn=n/2.(a+Un)
S60=60/2(1+119)
      =30 x 120
      =3600