Question

Quantos termos tem a P.G.(2,6,18,...,4374)?

Answer 1

q = 6/2 = 3


an = a1 . q ^n - 1

4374 = 2 . 3 ^n - 1

fatorando 4374 = 2 . 3 elevado a 7

2 . 3elevado a 7 = 2 .3 ^n - 1 cortando as bases 2 e 3

n - 1 = 7

n = 7 +1

n = 8

*************************M

Answer 2

 

 

an = a1 . q ^n - 1)

an= 4374a1= 2n= ?r=a2/a1 => 6/2 = 3 4374 = 2 . 3^( n - 1)
3^( n - 1) = 4374/23^( n - 1) = 21873^( n - 1) = 3^7  corta-se 3 (bases iguais). n - 1 = 7 n = 8