Respuesta :

myeliz048

You need to find S4 for the series -2 + 6 - 18... etc.

The common ratio is -3

[tex]Sn = \frac{a1 (1-r^{n})}{1-r}[/tex]

[tex]S4 = \frac{-2(1-(-3)^4}{1-(-3)} = \frac{-2(1-81)}{4} = \frac{160}{4} = 40[/tex]

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