The number of irrational terms in the expansion of $(3^{\frac{1}{8}}+5^{\frac{1}{4}})^{84}$ is

The coefficient of $x^3$ in the expansion of $(x - \frac{1}{x})^7$ is

Let the ratio of the fifth term from the beginning to the fifth term from the end in the binomial expansion of $(\sqrt[4]{2}+\frac{1}{\sqrt[4]{3}})^{n}$,in the increasing powers of $\frac{1}{\sqrt[4]{3}}$ be $\sqrt[4]{6}: 1$. If the sixth term from the beginning is $\frac{\alpha}{\sqrt[4]{3}}$,then $\alpha$ is equal to $.......$

The middle terms in the expansion of ${\left( {3x - \frac{{{x^3}}}{6}} \right)^9}$ are:

The coefficient of $x^4$ in $\left[ \frac{x}{2} - \frac{3}{x^2} \right]^{10}$ is:

The greatest term in the expansion of $\sqrt{3} \left( 1 + \frac{1}{\sqrt{3}} \right)^{20}$ is