Question

What is the first five terms in the geometric sequence An=(2)n-1

Answer 1

geometric sequence ?
do you mean
a(n)=2^(n-1)

Answer 2

Yes

Answer 3

put n=1 ,2, 3,4,5 in it

like this
a(2)=2^(2-1)=2^1=2

a(1)=2^(1-1)=2^0=1