Tính I=lim (n^2(3n+2))/(n+1)^2(n+3))

Ta có $\mathrm{I}=\lim \frac{{\mathrm{n}}^2\left(3\mathrm{n}+2\right)}{{\left(\mathrm{n}+1\right)}^2\left(\mathrm{n}+3\right)}$$=\lim \frac{3+\frac{2}{\mathrm{n}}}{{\left(1+\frac{1}{\mathrm{n}}\right)}^2\left(1+\frac{3}{\mathrm{n}}\right)}$$=3$

Chọn đáp án B.