# Math Help - sequence & series

1. ## sequence & series

pls teach me qn 15(ii).thks!

2. Here are few extra steps that should lead you to the answer:
1. Find a real number $a$ such that the sequence $(v_n)_{n\geqslant1}$ defined by $v_n=u_n-a$ is geometric with common ratio $k$.
2. Express $v_n$ in terms of $n$ and $k$.
3. Express $u_n$ in terms of $n$ and $k$.