JCECE Engineering JCECE Engineering Solved Paper-2006

  • question_answer
    The equation of the directrix of the parabola \[{{y}^{2}}+4y+4x+2=0\]is:

    A) \[x=-1\]                               

    B) \[x=1\]

    C) \[x=-\frac{3}{2}\]                            

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

    Correct Answer: D

    Solution :

    The equation of parabola is                 \[{{(y+2)}^{2}}=-4\left( x-\frac{1}{2} \right)\] Shifting the origin\[\left( \frac{1}{2},\,\,-2 \right)\], the equation of parabola becomes\[{{Y}^{2}}=-4X\] where   \[X=x-\frac{1}{2},\,\,Y=y+2\] An equation of its directrix is\[X=1\]. \[\therefore \]Required directrix,\[x=\frac{3}{2}.\]


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