Find a formula for the general term

Question

For each sequence, find a formula for the general term, a_n. Sequences start with n=1. For example, answer n^2 if given the sequence: 1,4,9,16,25,36,…

1. 1/2,1/4,/ 1/8,1/16,…

2. 3/16, 4/25, 5/36, 6/49

Answer 1

1,4,9,16,...

an=n^2

1/2,1/4,1/8,...

an = (1/2)(1/2^(n-1))

an =1/2^n

3/16,4/25,5/36,...

an=(3+n-1)/(n+3)^2

an = (n+2)/(n^2 +6n +9)