JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2013

  • question_answer
        In the expansion of\[{{(4-3x)}^{7}},\]when\[x=\frac{2}{3},\] the numerically greatest term is

    A)  \[{{T}_{4}}\]                    

    B)  \[{{T}_{3}}\]

    C)  \[{{T}_{5}}\]                    

    D)  None of these

    Correct Answer: B

    Solution :

                    \[{{(4-3x)}^{7}}={{4}^{7}}{{\left( 1-\frac{3x}{4} \right)}^{2}}\] Consider, \[{{\left( 1-\frac{3x}{4} \right)}^{7}}\]                 \[\frac{{{T}_{r+1}}}{{{T}_{r}}}=\frac{7-r+1}{r}.\frac{3}{4}.\frac{2}{3}\ge 1\] \[\Rightarrow \]               \[r\le 2.66\] \[\therefore \]  \[r=2\] Hence, the greatest term is \[{{T}_{3}}\].


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