Prove Theorem $2:$ Let $c_{1}$ and $c_{2}$ be real numbers with $c_{2}\neq 0.$ Suppose that $r^{2}-c_{1}r-c_{2} = 0$ has only one root $r_{0}.$ A sequence $\{a_{n}\}$ is a solution of the recurrence relation $a_{n} = c_{1}a_{n-1} + c_{2}a_{n-2}$ if and only if $a_{n} = \alpha_{1}r_{0}^{n} + \alpha_{2}nr_{0}^{n},$ for $n = 0,1,2,\dots,$ where $\alpha_{1}$ and $\alpha_{2}$ are constants.
