geometric sequence

Question

What are the first five terms in the geometric sequence a_n=(2)^n-1, starting with n=1

 

Please help..thank you

Answer 1

Start with a_1=2^(1-1)=2^0=1(by definition

Then a_2 = 2^(2-1) = 2^1=1

As you can see the exponent will increase by 1, so you need powers of two starting with 1, 2.

the next three terms are 2^2=4,2^3=8, and 2^4=16

 

Hope this is helpful