Answer
$$\eqalign{
& - 2,4, - 8,16, - 32 \cr
& {\text{The sequence is arithmetic}} \cr} $$
Work Step by Step
$$\eqalign{
& {a_n} = 2\left( {n + 3} \right) \cr
& {\text{Write the first five terms of the sequence}} \cr
& n = 1 \cr
& {a_1} = 2\left( {1 + 3} \right) = 8 \cr
& \cr
& n = 2 \cr
& {a_2} = 2\left( {2 + 3} \right) = 10 \cr
& \cr
& n = 3 \cr
& {a_3} = 2\left( {3 + 3} \right) = 12 \cr
& \cr
& n = 4 \cr
& {a_4} = 2\left( {4 + 3} \right) = 14 \cr
& \cr
& n = 5 \cr
& {a_5} = 2\left( {5 + 3} \right) = 16 \cr
& \cr
& - 2,4, - 8,16, - 32 \cr
& {\text{The sequence is arithmetic}} \cr} $$
