Use the picture to help you out.

Problem $4.$ Using the definitions of big O and $\backslash$Omega to show that

$($a$)6$n$2+20$n in O$($n$3)$

$($b$)50$log$2$n$+520$ in O$($log$2$n$)$

$($c$)6$n$2+20$n in $\backslash$Omega $($n$220)$