\(a=\sqrt[3]{2-\sqrt{3}}+\sqrt[3]{2+\sqrt{3}}\)
=>\(a^3=2-\sqrt{3}+2+\sqrt{3}+3\cdot\left(\sqrt[3]{2-\sqrt{3}}+\sqrt[3]{2+\sqrt{3}}\right)\cdot\sqrt[3]{\left(2-\sqrt{3}\right)\left(2+\sqrt{3}\right)}\)
=>\(a^3=4+3a\)
=>\(a^3-3a=4\)
\(\Leftrightarrow a^2-3=\dfrac{4}{a}\)
\(\left(a^2-3\right)^3\)
\(=\left(\dfrac{4}{a}\right)^3=\dfrac{64}{a^3}\)
\(C=\dfrac{64}{\left(a^2-3\right)^3}-3a\)
\(=64:\dfrac{64}{a^3}-3a\)
=a^3-3a
=4
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