Question

determinar a soma dos 6 primeiros termos da P.g -2, -6 , -18​

Answer 1

$> \: resolucao \\ \\ \geqslant \: progressao \: \: geometrica \\ \\ q = \frac{a2}{a1} = \frac{ - 6}{ - 2} = 3 \\ \\ = = = = = = = = = = = = = = \\ \\ > \: soma \: dos \: 6 \: primeiros \: \\ termos \: da \: pg \\ \\ sn = \frac{a1(q {}^{n } - 1) }{q - 1} \\ \\ sn = \frac{ - 2(3 {}^{6} - 1) }{3 - 1} \\ \\ sn = \frac{ - 2(729 - 1)}{2} \\ \\ sn = \frac{ - 2 \times 728}{2} \\ \\ sn = - 1 \times 728 \\ \\ sn = - 728 \\ \\ \geqslant \leqslant \geqslant \leqslant \geqslant \leqslant \geqslant \geqslant$