Question

Quantos termos tem a PG finita (3,6,12,...,3072)

Answer 1

$PG(3,6,12,...,3072)\\\\\\ a_{1} =3\\ a_{n} =3072\\q=2\\n=?\\\\\\ a_{n} = a_{1}* q^{n-1} \\\\\\ 3072 = 3* 2^{n-1} \\\\ 3*2^{10} = 3* 2^{n-1} \\\\ 3*2^{10} = 3* 2^{n-1} \\\\ 3*10=3*n-1\\\\ 30=3n-3\\\\ 30+3=3n\\\\ 33=3n\\\\ \frac{33}{3} =n\\\\ n=11$