Paper 2, Section I, A

Differential Equations
Part IA, 2010

Find the general solutions to the following difference equations for yn,nNy_{n}, n \in \mathbb{N}.

 (i) yn+33yn+1+2yn=0, (ii) yn+33yn+1+2yn=2n (iii) yn+33yn+1+2yn=(2)n (iv) yn+33yn+1+2yn=(2)n+2n.\begin{aligned} \text { (i) } & y_{n+3}-3 y_{n+1}+2 y_{n}=0, \\ \text { (ii) } & y_{n+3}-3 y_{n+1}+2 y_{n}=2^{n} \\ \text { (iii) } & y_{n+3}-3 y_{n+1}+2 y_{n}=(-2)^{n} \\ \text { (iv) } & y_{n+3}-3 y_{n+1}+2 y_{n}=(-2)^{n}+2^{n} . \end{aligned}