Question

what are the first five geometric sequence an= (3)^n-1, starting with ^n=1

Answer 1

\[a_n = 3^{n-1}\]
\[a_1 = 3^{0}=1\]
\[a_2= 3^{1}=3\]
\[a_3= 3^{2}=9\]
\[a_4 = 3^{3}=27\]
\[a_5 = 3^{5}81\]

Answer 2

or
\[a_n = 3^{n}-1\]
\[a_1 = 3^{1}-1=3-1=2\]
\[a_2 = 3^{2}-1=9-1=8\]
\[a_3 = 3^{3}-1=27-1=26\]
\[a_4 = 3^{4}-1=81-1=80\]
\[a_n5 = 3^{5}-1=243-1=\]

Answer 3

last one is
\[a_5 = 3^{5}-1=243-1=242\]