111樟樹高中

已知數列\(\langle\;a_n\rangle\;\)中，若\(\displaystyle a_n=\frac{3}{\sqrt{n^4+4n^2}}+\frac{6}{\sqrt{n^4+16n^2}}+\frac{9}{\sqrt{n^4+36n^2}}+\ldots+\frac{3n}{\sqrt{5n^4}}\)，則\(\displaystyle \lim_{n\to \infty}a_n=\)？
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