JEE Main & Advanced JEE Main Paper (Held On 09-Jan-2019 Evening)

  • question_answer
    If the system of linear equations
    \[x-4y+7z=g\]
    \[3y-5z=h\]
    \[-2x+5y-9z=k\]
    is consistent, then: [JEE Main Online Paper (Held On 09-Jan-2019 Evening]

    A) \[g+2h+k=0\]                           

    B)               \[g+h+2k=0\]

    C)               \[g+h+k=0\]                

    D)               \[2g+h+k=0\]

    Correct Answer: D

    Solution :

    \[x-4y+7z=g\] \[3y-5z=h\] \[-2x+5y-9z=k\] \[D=\left| \begin{align}   & 1\,\,\,\,\,\,\,\,-4\,\,\,\,\,\,\,\,\,\,\,\,\,7 \\  & 0\,\,\,\,\,\,\,\,\,\,\,\,3\,\,\,\,\,\,\,\,\,-5 \\  & -2\,\,\,\,\,\,\,\,\,5\,\,\,\,\,\,\,\,-9 \\ \end{align} \right|\] \[D=1(-27+25)-2\left( 20-21 \right)\] \[D=-2+2=0\] If system is consistent then \[{{D}_{1}}={{D}_{2}}^{~}={{D}_{3}}=0\] \[\left| \begin{align}   & 1\,\,\,\,\,\,\,\,-4\,\,\,\,\,\,\,\,\,\,\,\,\,g \\  & 0\,\,\,\,\,\,\,\,\,\,\,\,3\,\,\,\,\,\,\,\,\,\,\,\,\,h \\  & -2\,\,\,\,\,\,\,\,\,5\,\,\,\,\,\,\,\,\,\,\,\,\,k \\ \end{align} \right|=0\] \[1\left( 3k-5h \right)-2\left( -4h-3g \right)=0\] \[3k-5h+8h+6g=0\] \[6g+3h+3k=0\] \[2g+h+k=0\]


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