A sequence of terms $\displaystyle {U_n}$ is defined by $\displaystyle n\geq1$ by the recurrence relation $\displaystyle U_{n+1}=kU_n+2$, where $\displaystyle k$ is a constant. Given that $\displaystyle U_1=3$:

a) Find an expression in terms of $\displaystyle k$ for $\displaystyle U_2$.

Please tell me how to do this .