For the given expression, determine the dominant term and then use the dominant term to classify the algorithm in big-O terms and also in $\Omega$-notation.
So, I believe $n^3$ is the dominant term - but a plot of these shows that $n^3$ doesn't grow as fast as the function? Just starting a course in this and I still haven't got a solid grasp on it yet. I understood Big O should be an upper bound and Big Omega a lower. And how do I use the dominant term to determine the Big Omega?