JEE Main & Advanced Sample Paper JEE Main - Mock Test - 16

  • question_answer
    The image of the line \[2x-y=1\]in the line \[x+y=0\] is

    A) \[x+2y=-\frac{1}{3}\]   

    B) \[x-2y=1\]

    C) \[x+3y=-\frac{2}{3}\]   

    D) \[2x+y=\frac{1}{3}\]

    Correct Answer: B

    Solution :

    [b]:\[2x-y=1\Rightarrow x=\alpha ,y=2\alpha -1\] The image of the point \[(\alpha ,2\alpha -1)\]in the line \[x+y=0\]is given by \[\frac{x-\alpha }{1}=\frac{y-(2\alpha -1)}{1}=-2\frac{(\alpha +2\alpha -1)}{1+1}=1-3\alpha \] \[\therefore \]\[x=1-2\alpha ,y=2\alpha -1+1-3\alpha =-\alpha \] Elimination of\[\alpha \]gives the image \[x-2y=1\].


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