Given the geometric sequence: $\displaystyle {35},{\frac{{{5}}}{{{2}}}},{\frac{{{5}}}{{{28}}}}\ldots$

Find an explicit formula for $\displaystyle {a}_{{n}}$.
$\displaystyle {a}_{{n}}=$ Preview Question 6 Part 1 of 2  

Find $\displaystyle {a}_{{{8}}}=$ Preview Question 6 Part 2 of 2   .