I need help with this question from Data-Structure course.
I need to prove that the following polynomial is lower bounded by $n^k $, meaning I need to show that: 
$$ p(n) = b\_kn^k - b\_{k-1}n^{k-1}-b\_0n = \Omega(n^k) $$
So I have switched the Omega to inequlity and now I need to show that there exist constant $c$ and $n\_0$ that solve the following inequality:
$$ b\_kn^k - b\_{k-1}n^{k-1}-b\_0 n \ge c \cdot n^k $$ 
holds for $n \ge n\_0$. It is also given that $$ b\_k , b\_{k-1} , b\_0 > 0 \,.$$