How to isolate $n$ in the inequality $ 3n + 7n^3\gt c(17 + 34n^2) $? I have an equation 
$$ 3n + 7n^3\gt c\left(17 + 34n^2\right)
$$
and I want to turn this inequality into something like 
$$ n \gt c(\mbox{something that does not have}\ n)
$$
I don't know why but always get stumped at these types of questions. Any help would be appreciated, thanks.

Try putting it as
$$
n(7n^2+34cn+3)>17c
$$
Hopefully, the 2nd degree term at the left hand side can be put as $(n+\alpha)(n+\beta)$, where $\alpha$ and $\beta$ will probably depend on $c$
