31. sorozatok

a) \( \lim{ \frac{\sqrt{n^3+7}-n^2+n}{n^2+6n-\sqrt[3]{n^4}} } = ?\)

b) \( \lim{ \frac{\sqrt[3]{n^4-8n}+n^2+3n}{\sqrt{9n^4+1}-\sqrt{n^5+n^4}+n-n^2} } = ?\)

c) \( \lim{ \frac{\sqrt{n^4+7}-3n^2+n}{n^2+4n-\sqrt[5]{n^4}} } = ?\)