\begin{questions}
\item $2x(x-2)(x+2)= 2x(x^2-4)=2x^3-8x$.
\item $\begin{aligned}[t]
(1+3x)^2-2(x+1)(x-5) & =1+6x+9x^2-2(x^2-5x+x-5)\\
& =1+6x+9x^2-2x^2+8x+10\\
&=7x^2+14x+11.\end{aligned}$
\item $\left(3x-\sqrt{3}\right)^2=9x^2-6x\sqrt{3}+3$.
\item $\left(x+\dfrac{1}{x}\right)^2=x^2+2\times x\times \dfrac{1}{x}+\dfrac{1}{x^2}=x^2+2+\dfrac{1}{x^2}$.
\end{questions}
