Consider the following two functions f$1($n$)$ and f$2($n$)$:

f$1($n$)=6$n$^2+14$n $+5$

f$2($n$)=$ n$^3$

From the formal definition of Big$-$O notation f$($n$)=$ O$($g$($n$)),$ show

that f$1($n$)=$ O$($f$2($n$)).$