Deret geometri 1. 250+50+20+2 Jumlah 7 suku pertama barisan diatas 2)a. 2+6+18+54.....+1458 b.192+96+48+......+6 c.3+6+12+24+.....+384
Tolong jawab ya, dapet 45poin lhooooo:*
whongaliem2)a. 2+6+18+54.....+1458 ----> a = 2 : r = 3 ; Un 1458 Un = a . 1458 = 2 . = 729 = n - 1 = 6 n = 7 Sn = S7 = S7 = S7 = 2186 b.192+96+48+......+6 ------> a = 192 ; r = 1/2 ; Un = 6 Un = a . 6 = 192 . = = n - 1 = 5 n = 6 Sn = Sn = Sn = Sn = 192 . . 2 Sn = 3 . 63 . 2 Sn = 378 c.3+6+12+24+.....+384 -------> a = 3 ; r = 2 ; Un = 384 Un = a . 384 = 3 . = = 128 = n - 1 = 7 n = 8 Sn = S8 = S8 = S8 = 3.(255) S8 = 765 untuk soal no.1 cek kembali karena bukan deret geometri....
Un = a .
1458 = 2 .
= 729
=
n - 1 = 6
n = 7
Sn =
S7 =
S7 =
S7 = 2186
b.192+96+48+......+6 ------> a = 192 ; r = 1/2 ; Un = 6
Un = a .
6 = 192 .
=
=
n - 1 = 5
n = 6
Sn =
Sn =
Sn =
Sn = 192 . . 2
Sn = 3 . 63 . 2
Sn = 378
c.3+6+12+24+.....+384 -------> a = 3 ; r = 2 ; Un = 384
Un = a .
384 = 3 .
=
= 128
=
n - 1 = 7
n = 8
Sn =
S8 =
S8 =
S8 = 3.(255)
S8 = 765
untuk soal no.1 cek kembali karena bukan deret geometri....
a. Un = ar^n-1
1458=2.3^n-1
729=3^n-1
3^6 = 3^n-1
n=7
b. Un=ar^n-1
6=192.1/2^n-1
6/192=1/2^n-1
0,3125=1/2^n-1
(1/2)^5=1/2^n-1
n=6
c. Un=ar^n-1
384=3.2^n-1
128=2^n-1
2^7=2^n-1
n=8