JEE Main & Advanced Sample Paper JEE Main Sample Paper-20

  • question_answer
    The equation \[{{(5x-1)}^{2}}+{{(5y-2)}^{2}}=\]\[({{\lambda }^{2}}-4\lambda +4){{(3x+4y-1)}^{2}}\] represents an ellipse if\[\lambda \in \]

    A) \[(0,\,\,1]\]                        

    B) \[(-1,\,\,2)\]

    C) \[(2,\,\,3)\]                        

    D) \[(-1,\,\,0)\]

    Correct Answer: C

    Solution :

     \[{{\left( x-\frac{1}{5} \right)}^{2}}+{{\left( y-\frac{2}{5} \right)}^{2}}=({{\lambda }^{2}}-4\lambda +4){{\left( \frac{3x+4y-1}{5} \right)}^{2}}\]\[i.e.,\,\,\sqrt{{{\left( x-\frac{1}{5} \right)}^{2}}+{{\left( y-\frac{2}{5} \right)}^{2}}}=|\lambda -2|\left| \frac{3x+4y-1}{\sqrt{5}} \right|\]is an ellipse. If\[0<|\lambda -2|\,\,<1\,\,i.e.,\,\,\lambda \in (1,\,\,2)\cup (2,\,\,3)\]


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