$\lim\limits_{n \to \infty}\dfrac{2n^2 - \sqrt{n}+3}{3n^2 + 1}$.

设$y = y(x)$由参数方程$\begin{cases}x = 2e^{t}+1\\y=t^{3}-3t\end{cases}$所确定，求$\dfrac{dy}{dx}$.

设方程$\cos x^{2}+xy + y^{2}=3$确定了函数$y = y(x)$，求$\dfrac{dy}{dx}$.