Question

Calcular a Soma dos 7 primeiros termos da p.g (3,6.12...)

Answer 1

q =  6  = 2
      3
Sn = a1(1 - $q^{n} )$
            1 - q
S7 =  3 ( 1 - $2^{7} )$
            1 - 2
S7 = 3(1 - 128)
            -1
S7 = 3 .(- 127)
           -1
S7 = - 381
         - 1
S7 = 381

Bons estudos..(;

Answer 2

$PG(3,6.12...)\\\\ S_n=?\\ a_1=3\\ q= \frac{6}{3} \to 2\\ n=7\\\\\\ S_n= \frac{a_1*(q^{n}-1)}{q-1} \\\\\\ S_n= \frac{3*(2^{7}-1)}{2-1} \to\\\\ S_n= \frac{3*(128-1)}{1} \to\\\\ S_n= \frac{3*(127)}{1} \to \\\\S_n= \frac{381}{1} \to \\\\S_n=381$