J & K CET Engineering J and K - CET Engineering Solved Paper-2009

  • question_answer
    If \[0<a<b,\]then \[\underset{n\to \infty }{\mathop{\lim }}\,\,\,\frac{{{a}^{n}}+{{b}^{n}}}{{{a}^{n}}-{{b}^{n}}}\]

    A)  equals 0       

    B)  equals - 1

    C)  equals 1    

    D)  does not exist

    Correct Answer: B

    Solution :

    \[\underset{n\to \infty }{\mathop{\lim }}\,\,\frac{{{a}^{n}}+{{b}^{n}}}{{{a}^{n}}-{{b}^{n}}}=\underset{n\to \infty }{\mathop{\lim }}\,\frac{{{\left( \frac{a}{b} \right)}^{n}}+1}{{{\left( \frac{a}{b} \right)}^{n}}-1}\] \[=-1\] \[\left[ \text{since, 0 }\frac{a}{b}<1\,implies\,{{\left( \frac{a}{b} \right)}^{n}}\to 0\,as\,n\to \infty  \right]\]


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