Question

qual a soma dos termos da PG(2,4,...,1024)

Answer 1

a1 = 2
a1q = 4
q=  4/2 = 2 *****
an = a1q^n-1
1024 = 2 * 2^(n-1)
2^( n-1) = 1024/2 = 512 = 2^9
2^n-1  = 2^9
n - 1 = 9
n = 9 + 1
n = 10 *****

S10 =   a1 ( q^10    - 1) /( 2 - 1)
S10  = 2 ( 2^10  - 1) 
S10   = 2 ( 1024 - 1)
S10 = 2 * 1023  = 2046