JEE Main & Advanced Mathematics Conic Sections Question Bank Ellipse

  • question_answer
    The eccentricity of the curve represented by the equation \[{{x}^{2}}+2{{y}^{2}}-2x+3y+2=0\] is      [Roorkee 1998]

    A)            0     

    B)            1/2

    C)            \[1/\sqrt{2}\]                            

    D)            \[\sqrt{2}\]

    Correct Answer: C

    Solution :

               Equation \[{{x}^{2}}+2{{y}^{2}}-2x+3y+2=0\] can be written as                    \[\frac{{{(x-1)}^{2}}}{2}+{{\left( y+\frac{3}{4} \right)}^{2}}=\frac{1}{16}\]Þ\[\frac{{{(x-1)}^{2}}}{(1/8)}+\frac{{{\left( y+\frac{3}{4} \right)}^{2}}}{(1/16)}=1\],                    which is an ellipse with \[{{a}^{2}}=\frac{1}{8}\] and \[{{b}^{2}}=\frac{1}{16}\]                    \[\therefore \frac{1}{16}=\frac{1}{8}(1-{{e}^{2}})\] Þ\[{{e}^{2}}=1-\frac{1}{2}\]Þ\[e=\frac{1}{\sqrt{2}}\].


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