Answer
a) $32$ and $64$
b) $a_{n+1} = 2a_n$, $a_1 = 1$
c) $a_n = 2^{n-1}$
Work Step by Step
a) The terms are increasing in powers of two. Thus, the next two terms are $32$ and $64$.
b) The first term is $1$, so $a_1 = 1$
Since we're simply multiplying two to the previous term in order to get the next term, the recursive function would be:
$$a_{n+1} = 2a_n$$
c) We are simply multiplying the number $2$, $n-1$ amount of times (since $2^0$ would yield us $0$, the first term of the sequence).
$$a_n = 2^{n-1}$$