Answer
a) $1; 3; 9; 27; 81;$
b) $r=3$
c) See graph
Work Step by Step
We are given the sequence:
$$a_n=3^{n-1}.$$
a) Determine the first $5$ terms:
$$\begin{align*}
a_1&=3^0=1\\
a_2&=3^1=3\\
a_3&=3^2=9\\
a_4&=3^3=27\\
a_5&=3^4=81.
\end{align*}$$
b) The common ratio is the quotient between each number in the series and the number before it:
$$r=\dfrac{a_{n+1}}{a_n}=\dfrac{3^n}{3^{n-1}}=3.$$
c) Graph the terms $a_1,a_2,a_3,a_4,a_5$:
