JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
     \[\underset{n\to \infty }{\mathop{\lim }}\,\frac{n{{(2n+1)}^{2}}}{(n+2)({{n}^{2}}+3n-1)}=\]

    A)                 0

    B)                 2

    C)                 4

    D)                 \[\infty \]

    Correct Answer: C

    Solution :

                       \[\underset{n\to \infty }{\mathop{\lim }}\,\,\frac{n\,{{(2n+1)}^{2}}}{(n+2)\,\,({{n}^{2}}+3n-1)}=\underset{n\to \infty }{\mathop{\lim }}\,\,\,\frac{4{{n}^{3}}+4{{n}^{2}}+n}{{{n}^{3}}+5{{n}^{2}}+5n-2}\]                                                 \[=\underset{n\to \infty }{\mathop{\lim }}\,\frac{{{n}^{3}}\,\left( 4+\frac{4}{n}+\frac{1}{{{n}^{2}}} \right)}{{{n}^{3}}\left( 1+\frac{5}{n}+\frac{5}{{{n}^{2}}}-\frac{2}{{{n}^{3}}} \right)}=4\]


You need to login to perform this action.
You will be redirected in 3 sec spinner