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Find the sum of the geometric sequence –3, 15, –75, 375, … when there are 8 terms and select the correct answer below.

–195,312
195,312
292,968
–292,968

Respuesta :

caylus
Hello,

Answer B

[tex](-3)*(-5)^0\\ +(-3)*(-5)^1\\ +(-3)*(-5)^2\\ +(-3)*(-5)^3\\ +...\\ +(-3)*(-5)=\\\\ =(-3)*(1+(-5)+(-5)^2+(-5)^3+...+(-5)^7)\\ =-(3)* \dfrac{1-(-5)^8}{1-(-5)} \\ =-3* \dfrac{1-5^8}{6} \\\\ \boxed{=195312}\\ [/tex]

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