BCECE Engineering BCECE Engineering Solved Paper-2011

  • question_answer
    The term independent of \[x\]in \[{{\left[ \sqrt{\frac{x}{3}}+\sqrt{\frac{3}{2{{x}^{2}}}} \right]}^{10}}\] is

    A)  \[{{\,}^{10}}{{C}_{1}}\]                       

    B)         \[5/12\]               

    C)         1                                            

    D)         None of these

    Correct Answer: D

    Solution :

    \[{{T}_{r+1}}={{\,}^{10}}{{C}_{r}}{{\left( \sqrt{\frac{x}{3}} \right)}^{10-r}}{{\left( \sqrt{\frac{3}{2{{x}^{2}}}} \right)}^{r}}\] \[={{\,}^{10}}{{C}_{r}}{{\left( \frac{1}{\sqrt{3}} \right)}^{10-r}}{{\left( \sqrt{\frac{3}{2}} \right)}^{r}}{{x}^{\left( 5-\frac{r}{2}-r \right)}}\] Let \[{{\text{T}}_{\text{r+1}}}\]be the term independent of \[x.\]                 \[\therefore \]      \[5-\frac{r}{2}-r=0\]\[\Rightarrow \]\[\frac{3r}{2}=5\Rightarrow r=\frac{10}{3}\]                 \[\therefore \] r is not a whole number. \[\therefore \]Given expression does not have any term independent of \[x.\]


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