n^3 = theta(n^2)
We need to find a c_1, c_2, and n_0 such that c_1 * g(n) <= f(n) <= c_2 * g(n)
I found that c_1 * n^2 <= n^3 <= c_2 * n^2
I found c_1 = 1, c_2 = 1, n_0 = 1;