Find the term ${\mathrm{a}}_9$ in the sequence whose $n^{th}$ term is ${\mathrm{a}}_{\mathrm{n}}={(-1)}^{\mathrm{n}-1}{\mathrm{n}}^3$

Write the first five terms of the following sequence and obtain the corresponding series

$a_1=-1,a_n=\frac{a_{n-1}}{n},n\ge 2$

Write the first five terms of the following sequence and obtain the corresponding series

 $a_1=a_2=2,a_n=a_{n-1}-1,n>2$