Evaluate: $\frac{2 \cdot 3^{n+1} + 7 \cdot 3^{n-1}}{3^{n+2} - 2 \cdot (1/3)^{1-n}}$

Let $\frac{7}{2^{1/2} + 2^{1/4} + 1} = A + B \cdot 2^{1/4} + C \cdot 2^{1/2} + D \cdot 2^{3/4}$,then find the value of $A + B + C + D$.

$20^{2-3x^2} = (40\sqrt{5})^{3x^2-2}$,then $x$ is equal to

The least number among $\sqrt[3]{4}, \sqrt[4]{5}, \sqrt[4]{7}$ and $\sqrt[3]{8}$ is:

The rationalising factor of $a^{1/3} + a^{-1/3}$ is

Evaluate: $\sqrt{3 + \sqrt{5}}$