JEE Main & Advanced Mathematics Applications of Derivatives Question Bank Tangent and Normal

  • question_answer
    An equation of the tangent to the curve \[y={{x}^{4}}\] from the point (2, 0) not on the curve is                                [RPET 2000]

    A)            \[y=0\]

    B)            \[x=0\]

    C)            \[x+y=0\]

    D)            None of these

    Correct Answer: A

    Solution :

               Let the point of contact be \[(h,k)\], where \[k={{h}^{4}}\]. Tangent is \[y-k=4{{h}^{3}}(x-h)\],       \[\left[ \because \,\frac{dy}{dx}=4{{x}^{3}} \right]\]            It passes through (2, 0),  \ \[-k=4{{h}^{3}}(2-h)\]\[\]            Þ  \[h=0\]or 8/3 ,  \ \[k=0\] or (8/3)4            \ Points of contact are (0, 0) and \[\left( \frac{8}{3},\,{{\left( \frac{8}{3} \right)}^{4}} \right)\]            \ Equation of tangents are            \[y=0\] and\[y-{{\left( \frac{8}{3} \right)}^{4}}=4{{\left( \frac{8}{3} \right)}^{3}}\left( x-\frac{8}{3} \right)\].


You need to login to perform this action.
You will be redirected in 3 sec spinner