For each of the following pairs of functions, either f$($n$)$ is O$($g$($n$)),$ f$($n$)$ is $\backslash$Omega $($g$($n$)),$ or f$($n$)$ is $\backslash$Theta $($g$($n$)).$ f$($n$)=2^($n$+1)+3^($n$-1)$ ; g$($n$)=3^$n