JEE Main & Advanced Mathematics Differential Equations Question Bank Formation of differential equations

  • question_answer
    The differential equation of the family of curves \[{{y}^{2}}=4a(x+a)\], where a is an arbitrary constant, is

    A)                 \[y\text{ }\left[ 1+{{\left( \frac{dy}{dx} \right)}^{2}} \right]=2x\frac{dy}{dx}\]       

    B)                 \[y\text{ }\left[ 1-{{\left( \frac{dy}{dx} \right)}^{2}} \right]=2x\frac{dy}{dx}\]

    C)                 \[\frac{{{d}^{2}}y}{d{{x}^{2}}}+2\frac{dy}{dx}=0\]           

    D)                 \[{{\left( \frac{dy}{dx} \right)}^{3}}+3\,\frac{dy}{dx}+y=0\]

    Correct Answer: B

    Solution :

                       Given \[{{y}^{2}}=4a(x+a)\]. Differentiating, \[2y\,\left( \frac{dy}{dx} \right)=4a\]         Eliminating a from (i) and (ii), required equation is                                 \[y\text{ }\left[ 1-{{\left( \frac{dy}{dx} \right)}^{2}} \right]=2x\frac{dy}{dx}\].


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