Question

Na PG ( 4, 2,...) determine a soma dos 10 primeiros termos

Answer 1

a1 = 4
a2 = 2
q = 2/4 = 1/2 **
n = 10

S10 =  4 [ ( 1/2)¹⁰  - 1/1)/( 1/2 - 1)
S10 = 4 ( 1/1024  - 1/1) / ( -1/2)
S10 = 4 ( - 1023/1024 ) /( - 1/2)
S10 = ( -4092/1024) / ( - 1/2)
S10 = - 4092/1024 *  -2/1  = 8184/1024  =1023/128