A sequence u1,u2,u3,… u_1, u_2, u_3, \dots\,u1,u2,u3,… is defined by
u1=8un+1=un+k,n≥1 \begin{aligned}u_1 &= 8 \\u_{n+1} &= u_n + k, \quad n \geq 1\end{aligned} u1un+1=8=un+k,n≥1Given u5=32u_5 = 32u5=32
Find the value of kkk.
Find an expression for un u_n\,un in terms of nnn.