Chọn phương án C.

Dùng máy tính cầm tay:

1. Dùng chức  năng r, với \(x=999999\)
   
2. Kết quả xấp xỉ bằng \(0\)
   

Chọn phương án C.

\(\begin{aligned}
L&=\lim\left(\sqrt[3]{n^3+1}-\sqrt[3]{n^3+2}\right)\\
&=\lim\dfrac{\left(\sqrt[3]{n^3+1}-\sqrt[3]{n^3+2}\right)\left(\sqrt[3]{\left(n^3+1\right)^2}+\sqrt[3]{\left(n^3+1\right)\left(n^3+2\right)}+\sqrt[3]{\left(n^3+2\right)^2}\right)}{\sqrt[3]{\left(n^3+1\right)^2}+\sqrt[3]{\left(n^3+1\right)\left(n^3+2\right)}+\sqrt[3]{\left(n^3+2\right)^2}}\\
&=\lim\dfrac{\left(n^3+1\right)-\left(n^3+2\right)}{\sqrt[3]{n^6+2n^3+1}+\sqrt[3]{\left(n^3+1\right)\left(n^3+2\right)}+\sqrt[3]{n^6+4n^3+4}}\\
&=\lim\dfrac{-1}{\sqrt[3]{n^6\left(1+\dfrac{2}{n^3}+\dfrac{1}{n^6}\right)}+\sqrt[3]{n^6\left(1+\dfrac{1}{n^3}\right)\left(1+\dfrac{2}{n^3}\right)}+\sqrt[3]{n^6\left(1+\dfrac{4}{n^3}+\dfrac{4}{n^6}\right)}}\\
&=\lim\dfrac{-1}{n^2\sqrt[3]{1+\dfrac{2}{n^3}+\dfrac{1}{n^6}}+n^2\sqrt[3]{\left(1+\dfrac{1}{n^3}\right)\left(1+\dfrac{2}{n^3}\right)}+n^2\sqrt[3]{1+\dfrac{4}{n^3}+\dfrac{4}{n^6}}}\\
&=\lim\dfrac{\dfrac{-1}{n^2}}{\sqrt[3]{1+\dfrac{2}{n^3}+\dfrac{1}{n^6}}+\sqrt[3]{\left(1+\dfrac{1}{n^3}\right)\left(1+\dfrac{2}{n^3}\right)}+\sqrt[3]{1+\dfrac{4}{n^3}+\dfrac{4}{n^6}}}\\
&=\dfrac{0}{\sqrt[3]{1+0+0}+\sqrt[3]{\left(1+0\right)\left(1+0\right)}+\sqrt[3]{1+0+0}}=0.
\end{aligned}\)