Question

Calcule a 9º termo da P.G. (1/9,1/3,...)?

Answer 1

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a₉=an=?   a₁=1/9      n=9      q=1/3÷1/9=1/3×9/1=3

$a_n=a_1.q^{n-1} \\ \\ a_9= \frac{1}{9} .3^{9-1} \\ \\ a_9= \frac{1}{9} .3^8 \\ \\ a_9= \frac{3^8}{3^2} \\ \\ a_9=3^8\div3^2=3^{8-2}=3^6 \\ \\ a^9=3^6 \\ \\ a_9=729$