quantos termos tem a pg ( -1/120,1/60,-1/30,...,64/15).... Pergunta de ideia dealessandramh15

March 2022 1 22 Report

quantos termos tem a pg ( -1/120,1/60,-1/30,...,64/15)

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$Dados\to \left\{\begin{array}{ccc}\boxed{a_n = a_1*q^{n-1}}\\\\a_1 = -\frac{1}{120} \\\\a_n = \frac{64}{15} \\\\q = -2\\\\n=\ ?\end{array}\right$

$Resolu\c{c}\~ao\to \left\{\begin{array}{ccc} \frac{64}{15} = -\frac{1}{120}*(-2)^{n-1} \\\\(-2)^{n-1} = \frac{ \frac{64}{15} }{ -\frac{1}{120} }\\\\(-2)^{n-1} = \frac{64}{15}*-120\\\\(-2)^{n-1} = -512\\\\(-2)^{n-1} = (-2)^{9}\\\\n-1 = 9\\\\\boxed{\boxed{n = 10}} \end{array}\right$

Espero ter ajudado. :))

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alessandramh15 vlww :)

IzzyKoushiro Nada!

Quais sao os cincos primeiros termos da PG em que a1=4 e q=6 ??

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Quais sao os cincos primeiros termos da PG em que a1=4 e q=6 ??

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