2.147. $\frac{4}{\sqrt[4]{13}-\sqrt[4]{9}}$.

Express the above text in English, keeping the original text's line breaks and format, and output the translation result directly. 

2.147. $\frac{4}{\sqrt[4]{13}-\sqrt[4]{9}}$.
Solution.

$$
\begin{aligned}
& \frac{4}{\sqrt[4]{13}-\sqrt[4]{9}}=\frac{4\left(\sqrt[4]{13^{3}}+\sqrt[4]{13^{2} \cdot 9}+\sqrt[4]{13 \cdot 9^{2}}+\sqrt[4]{9^{3}}\right)}{(\sqrt[4]{13}-\sqrt[4]{9})\left(\sqrt[4]{13^{2} \cdot 9}+\sqrt[4]{13 \cdot 9^{2}}+\sqrt[4]{9^{3}}\right)}= \\
& =\frac{4(\sqrt[4]{13}+\sqrt[4]{9})\left(\sqrt[4]{13^{2}}+\sqrt[4]{9^{2}}\right)}{13-9}=(\sqrt[4]{13}+\sqrt[4]{9})(\sqrt{13}+3)
\end{aligned}
$$

Answer: $(\sqrt[4]{13}+\sqrt[4]{9})(\sqrt{13}+3)$