Hitunglah jumlah 8 suku pertama dari deret 5+20+80+320+....

Materi geometri.

Diket :
a = 5
r = 80/20 = 4

Ditanya S8?

Rumus umum Sn = a ( (r^n) - 1 ) / ( r - 1 )

S₈ = a ( (r^8) - 1 ) / ( r - 1 )
S₈ = 5 ( (4^8) - 1 ) / ( 4 - 1 )
S₈ = 5 ( 65.535 ) / 3
S₈ = 5 ( 21.845 )
S₈ = 109.225

Jadikan jawabannya yg terbaik thanks

Hai Bastiani155

U1 = 5
U2 = 20
U3 = 80
U4 = 320
U5 = 1.280
U6 = 5.120
U7 = 20.480
U8 = 81.920

5 + 20 + 80 + 320 + 1.280 + 5.120 + 20.480 + 81. 920 = 109.225.

°•Semoga Membantu•°