Question

A soma dos 12 termos da pg( 7,14)

Answer 1

P.G.(7,14,
q = a 2 / a 1
q = 14/7
q = 2
S 12 = a 1 .(q^n    -   1 )  /  q - 1
S 12 = 7 . (2^12    -  1 )  / 2 - 1
S 12 = 7 . (4096  -  1 )  / 1
S 12 = 7 .(4095) / 1
S 12 = 28665 / 1
S 12 = 28665