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

  • question_answer
    Consider the set of all lines \[px+qy+r=0\] such that \[3p+2q+4r=0\]. Which one of the following statements is true? [JEE Main Online Paper (Held On 09-Jan-2019 Morning]

    A) The lines are not concurrent

    B) The lines are concurrent at the point\[\left( \frac{3}{4},\,\,\frac{1}{2} \right)\]

    C) The lines are all parallel

    D) Each line passes through the origin

    Correct Answer: B

    Solution :

    Given lines are \[px\text{ }+\text{ }qy\text{ }+\text{ }r\text{ }=\text{ }0\,\,\,\,\,\,.......\,(1)\] \[\And \,\,\,3p\,\,+\,\,2q\,\,+\,\,4r\,\,=\,\,0\text{ }...\text{ }\left( 2 \right)\] \[\therefore \] (2) can be written as \[\frac{3}{4}p\,\,+\,\,\frac{q}{2}\,+\,r\,\,=\,\,0\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,......\,(3)\] from (a) & (c) \[x\,\,=\,\,\frac{3}{4},\,\,\,\,y\,\,=\,\,\frac{1}{2}\]


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