Question

Quantos termos tem a P .G. ( 13,26,..... 1664)? ( An = A 1 .Q n - 1 )

Answer 1

an = a1 * q^n-1
1664 = 13 * 2^n-1
2^n-1 = 1664 / 13
2^n-1 = 128
2^n-1 = 2^7
n-1 = 7
n = 7 + 1
n = 8