JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2007

  • question_answer
        If\[\overrightarrow{a},\overrightarrow{b},\overrightarrow{c}\]are non-coplanar vectors and\[\lambda \]is a real number, then the vectors\[\overrightarrow{a}+2\overrightarrow{b}+3\overrightarrow{c},\]and\[\lambda \overrightarrow{b}+4\overrightarrow{c}\]and\[(2\lambda -1)\overrightarrow{c}\]are non-coplanar for

    A)  all values of k

    B)  all except one value of k

    C)  all except two values of X

    D)  no value of k

    Correct Answer: C

    Solution :

                    The three vectors \[(\overrightarrow{a}+2\overrightarrow{b}+3\overrightarrow{c}),(\lambda \overrightarrow{b}+4\overrightarrow{c})\]and\[(2\lambda -1)\overrightarrow{c}\]are coplanar, if                 \[\left| \begin{matrix}    1 & 2 & 3  \\    0 & \lambda  & 4  \\    0 & 0 & 2\lambda -1  \\ \end{matrix} \right|=0\] \[\Rightarrow \]               \[(2\lambda -1)(\lambda )=0\] \[\Rightarrow \]               \[\lambda =0,\frac{1}{2}\] \[\therefore \]These three vectors are non-coplanar for all except two values of\[\lambda \]\[\left( i.e.,0,\frac{1}{2} \right)\].


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