BCECE Engineering BCECE Engineering Solved Paper-2001

  • question_answer
    The 6th term in expansion of \[{{\left( 2{{x}^{2}}-\frac{1}{3{{x}^{2}}} \right)}^{10}},\]is:

    A) \[\frac{4580}{17}\]                         

    B)  \[-\frac{896}{27}\]         

    C)         \[\frac{5580}{17}\]        

    D)         none of these

    Correct Answer: B

    Solution :

    The general term in the expansion of \[{{\left( 2{{x}^{2}}-\frac{1}{3{{x}^{2}}} \right)}^{10}}\]is \[{{T}_{r+1}}={{\,}^{n}}{{C}_{r}}{{(2{{x}^{2}})}^{n-r}}{{\left( -\frac{1}{3{{x}^{2}}} \right)}^{r}}\] \[\therefore \]6th term is \[{{T}_{5+1}}={{\,}^{10}}{{C}_{5}}{{(2{{x}^{2}})}^{10-5}}{{\left( -\frac{1}{3{{x}^{2}}} \right)}^{5}}\] \[=-\frac{10!}{5!5!}{{\left( \frac{2}{3} \right)}^{5}}\] \[=-\frac{10\times 9\times 8\times 7\times 6}{5\times 4\times 3\times 2\times 1}\times \frac{{{2}^{5}}}{{{3}^{5}}}\] \[=-\frac{896}{27}\]


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