JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2005

  • question_answer
        \[\underset{x\to \infty }{\mathop{\lim }}\,{{\left( \frac{{{x}^{2}}+5x+3}{{{x}^{2}}+x+2} \right)}^{x}}\]is equal to:

    A)  \[{{e}^{4}}\]                                     

    B)  \[{{e}^{2}}\]

    C)  \[{{e}^{3}}\]                                     

    D)  \[e\]

    Correct Answer: A

    Solution :

                    \[\underset{x\to \infty }{\mathop{\lim }}\,\left[ 1+\frac{4x+1}{{{x}^{2}}+x+2} \right]=\underset{x\to \infty }{\mathop{\lim }}\,{{[{{(1+\alpha )}^{1/\alpha }}]}^{\alpha x}}\] when \[\alpha =\frac{4x+1}{{{x}^{2}}+x+2}\]                 \[=\frac{4+\frac{1}{x}}{x\left( x+\frac{1}{x}+\frac{2}{{{x}^{2}}} \right)}\to 0\]     as\[x\to \infty \] and        \[\alpha x=\frac{4+\frac{1}{x}}{1+\frac{1}{x}+\frac{2}{{{x}^{2}}}}\to 4as\,x\to \infty \] Given limit \[={{e}^{4}}\]


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