Jawabanmu

Jawaban paling cerdas!
2014-03-31T22:48:14+07:00
A. U1 = 5
r= U2/U1 = 15/5 = 3
Un = 32.805
Un = U1 * r^(n-1) = 32.805
5* 3 ^ (n-1) = 32.805
3^(n-1) = 32.805/5
3^(n-1) = 6.561 = 3^8
n-1 = 8
n = 8 + 1 = 9


b. U1 = -1/2
b. U1 = -1/2
r = 1/ (-1/2) = -2
Un = -512
Un = U1 * -2 ^ (n-1) = -512
-1/2 * -2^ (n-1) = -512
-2 ^ (n-1) = -512 / (-1/2)
-2^ (n-1 ) = 1024 = -2^10
n-1 = 10
n=11
terimakasih banyak ya;)
2014-03-31T23:10:24+07:00
A)32.805=5x3^n-1
3^n-1=32.805:5
3^n-1=6561

b)-512=-1/2x(-2)^n-1
(-2)^n-1=-512:(-1/2)
(-2)^n-1=1024

cuma bisa segini maaf
a. 5,15,45...32.805
a = 5 , U2 = 15, maka r = U2/a =15/5 = 3. Un = 32805. 32805 = ar^n-1. 32805 = 5 x 3^n-1. 6561 = 3^n-1. 3^8 = 3^n-1. n = 8+1. n = 9. jadi, banyak suku adalah 9
sudah dijawab:) terimakasih