Question

Determine o número de termos da PG(1,2...256)

Answer 1

$a_1=1 \\ q=2 \\ a_n=256 \\ n=\,? \\ \\ a_n=a_1\cdot q^{n-1} \\ \\ 256=1\cdot2^{n-1} \\ \\ 256=2^{n-1} \\ \\ 2^{n-1}=2^8 \\ \\ n-1=8 \\ \\ \boxed{n=9}$