CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2000

  • question_answer
    If T denotes the r th term in the expansion of \[{{\left[ x+\frac{1}{x} \right]}^{23}},\]then:

    A)  \[{{T}_{12}}={{T}_{13}}\]

    B)                                         \[{{x}^{2}}{{T}_{13}}={{T}_{12}}\]           

    C)         \[{{T}_{12}}=x{{T}_{12}}\]                          

    D)         \[{{T}_{12}}+{{T}_{13}}=25\]

    E)         \[{{x}^{2}}{{T}_{12}}={{T}_{13}}\]

    Correct Answer: E

    Solution :

    \[\therefore \]  \[{{T}_{12}}{{=}^{23}}{{C}_{11}}{{x}^{11}}{{\left( \frac{1}{x} \right)}^{12}}{{=}^{23}}{{C}_{11}}\frac{1}{x}\] and        \[{{T}_{13}}{{=}^{23}}{{C}_{12}}{{x}^{12}}{{\left( \frac{1}{x} \right)}^{11}}\] \[\Rightarrow \]               \[{{T}_{13}}{{=}^{23}}{{C}_{11}}x\] \[\Rightarrow \]               \[{{T}_{13}}={{x}^{2}}\,{{\,}^{23}}{{C}_{11}}\frac{1}{x}\]                 \[={{x}^{2}}{{T}_{12}}\]


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