Question

Calcule a soma da P.G. infinita (-1, 1/4, -1/16, ...)

Answer 1

$Dados\to \left\{\begin{array}{ccc}Sn = \frac{a_1}{1-q} \\\\a_1 = -1\\q = - \frac{1}{4}\end{array}\right$

$Resolu\c{c}\~ao\to \left\{\begin{array}{ccc}Sn = \frac{a_1}{1-q} \\\\S_n = \frac{-1}{1-( -\frac{1}{4}) }\\\\S_n = \frac{-1}{1+ \frac{1}{4}} \\\\S_n = \frac{-1}{ \frac{5}{4} }\\\\S_n = -1* \frac{4}{5}\\\\\boxed{S_n = - \frac{4}{5} } \end{array}\right$

Espero ter ajudado. :))