J & K CET Engineering J and K - CET Engineering Solved Paper-2006

  • question_answer
    The term independent of x in the expansion of \[{{\left( {{x}^{3}}+\frac{2}{{{x}^{2}}} \right)}^{15}}\] is

    A)  \[{{T}_{7}}\]

    B)  \[{{T}_{8}}\]

    C)  \[{{T}_{9}}\]

    D)  \[{{T}_{10}}\]

    Correct Answer: D

    Solution :

    General term,  \[{{T}_{r+1}}{{=}^{15}}{{C}_{r}}\,{{({{x}^{3}})}^{15-r}}{{\left( \frac{2}{{{x}^{2}}} \right)}^{r}}\] \[{{=}^{15}}{{C}_{r}}{{x}^{45-5r}}{{(2)}^{r}}\] For term independent of x, put \[45-5r=0\] \[\Rightarrow \] \[5r=45\] \[\Rightarrow \] \[r=9\] \[\therefore \]    Independent term \[={{T}_{1+9}}={{T}_{10}}\]


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