Question

Numa P.G (2,1..),calcule o décimo primeiro termo

Answer 1

$a_{11}=a_1.q^{10}\\ \\ a_{11}=2.(\frac{1}{2})^{10}\\ \\ a_{11}=2.\frac{1}{1024}\\ \\ a_{11}=\frac{1}{512}$

Answer 2

$a_n=a_1\cdot q^{n-1}$

$(2,1,\dots)$

$q=\dfrac{1}{2}$

$a_{11}=2\cdot\left(\dfrac{1}{2}\right)^{11-1}$

$a_{11}=2\cdot\left(\dfrac{1}{2}\right)^{10}$

$a_{11}=2\cdot\dfrac{1}{2^{10}}$

$a_{11}=\dfrac{2}{2^{10}}$

$a_{11}=2^{1-10}$

$a_{11}=2^{-9}$

$a_{11}=\dfrac{1}{512}$