Question

dada a PG (4,8,16,...,1024) determine quantos termos existem nessa PG

Answer 1

a1=8
razão=8/4=2
an=1024
n=?

an=a1.q^n-1
1024=8.2^n-1
1024/8=2^n-1
128=2^n-1
2^7=2^n-1
2^n-1=2^7
n-1=7
n=7+1
n=8