I understand how to prove a function f(n) is $\Omega(g(n))$ - just find a positive $c$ and $a$ such that $ cg(x)) \leq f(x) $ for all $ x \gt a$ - but I'm not sure how to begin a proof that says $f(n) \not \subseteq \Omega (g(n))$.
The specific problem I'm working on is: $ f(n)=2^{n}, g(n)=2^{n+1}$ (trivial, I know)