JEE Main & Advanced JEE Main Paper (Held On 11-Jan-2019 Morning)

  • question_answer
    If the system of linear equations
    \[2x+2y+3z=a\]
    \[3x-y+5z=b\]
    \[x-3y+2z=c\]
    where a, b, c are non-zero real numbers, has more than one solution, then
    [JEE Main Online Paper (Held On 11-Jan-2019 Morning]

    A) \[b+c-a=0\]                              

    B)               \[a+b+c=0\]

    C)               \[b-c+a=0\]                              

    D)               \[b-c-a=0\]

    Correct Answer: D

    Solution :

    We have,\[A=\left[ \begin{matrix}    2 & 2 & 3  \\    3 & -1 & 5  \\    1 & -3 & 2  \\ \end{matrix} \right],X=\left[ \begin{matrix}    x  \\    y  \\    z  \\ \end{matrix} \right]\]and\[B=\left[ \begin{matrix}    a  \\    b  \\    c  \\ \end{matrix} \right]\] Here, \[\left| A \right|=0\] Since, the system of linear equations has more than one solution, so (adj A) = 0 \[\Rightarrow \left[ \begin{matrix}    13 & -13 & 13  \\    -1 & 1 & -1  \\    -8 & 8 & -8  \\ \end{matrix} \right]=\left[ \begin{matrix}    a  \\    b  \\    c  \\ \end{matrix} \right]=\left[ \begin{matrix}    0  \\    0  \\    0  \\ \end{matrix} \right]\]\[\Rightarrow b=a+c\]


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