JEE Main & Advanced Mathematics Rectangular Cartesian Coordinates Question Bank Transformation of axes and Locus

  • question_answer
    The locus of the moving point P, such that 2PA = 3PB where A is (0,0) and B is (4,-3), is [AMU 1980]

    A) \[5{{x}^{2}}-5{{y}^{2}}-72x+54y+225=0\]

    B) \[5{{x}^{2}}-5{{y}^{2}}+72x+54y+225=0\]

    C) \[5{{x}^{2}}+5{{y}^{2}}+72x+54y+225=0\]

    D) \[5{{x}^{2}}+5{{y}^{2}}-72x+54y+225=0\]

    Correct Answer: D

    Solution :

    Let \[P(h,\,\,k).\] Given \[2PA=3PB\,\,\Rightarrow \,\,4P{{A}^{2}}=9P{{B}^{2}}\] \[\Rightarrow \,\,4\,({{h}^{2}}+{{k}^{2}})=9\,[{{(h-4)}^{2}}+{{(k+3)}^{2}}]\] \[\Rightarrow \,\,5{{h}^{2}}+5{{k}^{2}}-72h+54k+225=0\] Hence the locus of point P is given by \[5{{x}^{2}}+5{{y}^{2}}-72x+54y+225=0\].


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