JEE Main & Advanced JEE Main Paper Phase-I (Held on 08-1-2020 Evening)

  • question_answer
    If a hyperbola passes through the point P (10, 16) and it has vertices at \[\left( \pm \,6,\text{ }0 \right)\] then the equation of the normal to it at P is                                                                                              [JEE MAIN Held on 08-01-2020 Evening]

    A) \[x+2y=42\]     

    B) \[2x+5y=100\]

    C) \[x+3y=58\]     

    D) \[3x+4y=94\]

    Correct Answer: B

    Solution :

    Let hyperbola \[=\frac{{{x}^{2}}}{36}-\frac{{{y}^{2}}}{{{b}^{2}}}=1\] \[\therefore \] (10, 16) lies on it \[\Rightarrow \,\,\,\,\,\,\frac{100}{36}-\frac{256}{{{b}^{2}}}=1\]   \[\Rightarrow \,\,\,\,\,\,\frac{64}{36}-\frac{256}{{{b}^{2}}}\] \[\Rightarrow \,\,\,\,\,\,{{b}^{2}}=144\]    \[\Rightarrow \,\,\,\,\,\,b=12\]     \[\therefore \] Equation of normal \[\frac{x-10}{\frac{10}{36}}=\frac{y-16}{\left( - \right)\frac{16}{144}}\] \[\Rightarrow \] \[2x-20=-5y+80\] \[\Rightarrow \]  \[2x+5y=100\]


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