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

  • question_answer
    The straight line \[y=m(x-a)\] meets the parabola \[{{y}^{2}}=4ax\] in  two distinct points for

    A)  all\[m\in R\]                     

    B)  all\[m\in [-1,\,\,1]\]

    C)  all\[m\in R-\{0\}\]          

    D)  None of these

    Correct Answer: C

    Solution :

    \[{{y}^{2}}=4a\left( \frac{y+am}{m} \right)i.e.,\,\,m{{y}^{2}}-4ay-4{{a}^{2}}m=0\] \[m\ne 0;\,\,16{{a}^{2}}+16{{a}^{2}}{{m}^{2}}>0\]which is true\[\forall \,m\]. \[\therefore \]  \[m\in R-\{0\}\]


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