hitunglah jumlah deret geometri 3+1+1/3+... sampai suku ke-6

a=3
r=1/3
U4=1/9
U5=1/27
U6=1/81

Cara manual..

U1=3
U2 =1
U3=1/3
U4=1/9
U5=1/27
U6=1/81

S6 = u1+u2+u3+u4+u5+u6
= 3+1+1/3+1/9+1/27+1/81
= 4 + 27/81+9/81+3/81+1/81
= 4+ 40 /81
= 324 /81 +40/81
= 364 /81


Cara rumus
S6 = u1 ×( 1-r^n) / (1-r)
= 3× ( 1- (1/3^6)) / 1-1/3
= 3 × ( 1- 1/ 729) / ( 1-1/3)
= 3× ( 729-1) / 729 ÷ ( 3-1)/3
= 3× 728 /729 ×3 /2
=6552/1458
= 364 /81