Question

Na P.G. (3,6,12), CALCULE

Answer 1

a)
$P.G.(3,6,12)\\ a_1=3\\ q=\frac{a_2}{a_1}=\frac{6}{3}=2\\\\ a_n=a_1.q^{n-1}\\ a_8=3.2^{8-1}\\ a_8=3.2^7\\ a_8=3.128\\ a_8=384$

b)
$a_n=a_1.q^{n-1}\\ 3072=3.2^{n-1}\\ 3.2^{n-1}=3072\\ 2^{n-1}=\frac{3072}{3}\\ 2^{n-1}=1024\\ 2^{n-1}=2^{10}\\ n-1=10\\ n=10+1\\ n=11$

3072 é o 11º termo.