If your ultimate objective is to find the limit, as n goes to infinity, divide both numerator and denominator by the "dominant" term, $\displaystyle x^5$.
If your ultimate objective is to find the limit, as n goes to infinity, divide both numerator and denominator by the "dominant" term, $\displaystyle x^5$.
That was what I did next , then apply the combination rules which gave me the limit to be 2.