JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    If \[a,\ b,\ c,\ d\] are positive, then \[\underset{x\to \infty }{\mathop{\lim }}\,{{\left( 1+\frac{1}{a+bx} \right)}^{c+dx}}=\] [EAMCET 1992]

    A)                 \[{{e}^{d/b}}\]

    B)                 \[{{e}^{c/a}}\]

    C)                 \[{{e}^{(c+d)/(a+b)}}\]

    D)                 \[e\]

    Correct Answer: A

    Solution :

                       \[\underset{x\to \infty }{\mathop{\lim }}\,\,{{\left( 1+\frac{1}{a+bx} \right)}^{c+dx}}=\underset{x\to \infty }{\mathop{\lim }}\,\,{{\left\{ {{\left( 1+\frac{1}{a+bx} \right)}^{a+bx}} \right\}}^{\frac{c+dx}{a+bx}}}={{e}^{d/b}}\]                        \[\left\{ \because \,\,\underset{x\to \infty }{\mathop{\lim }}\,\,{{\left( 1+\frac{1}{a+bx} \right)}^{a+bx}}=e \right.\]and \[\left. \underset{x\to \infty }{\mathop{\lim }}\,\frac{c+dx}{a+bx}=\frac{d}{b} \right\}\].


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