Medium MCQ +4 / -1 PYQ · JEE Mains 2022

The differential equation of the family of circles passing through the points $(0,2)$ and $(0,-2)$ is :

  1. A $2 x y \frac{d y}{d x}+\left(x^{2}-y^{2}+4\right)=0$ Correct answer
  2. B $2 x y \frac{d y}{d x}+\left(x^{2}+y^{2}-4\right)=0$
  3. C $2 x y \frac{d y}{d x}+\left(y^{2}-x^{2}+4\right)=0$
  4. D $2 x y \frac{d y}{d x}-\left(x^{2}-y^{2}+4\right)=0$

Solution

<p>Family of circles passing through the points (0, 2) and (0, $-$2)</p> <p>${x^2} + (y - 2)(y + 2) + \lambda x = 0,\,\lambda \in R$</p> <p>${x^2} + {y^2} + \lambda x - 4 = 0$ ...... (1)</p> <p>Differentiate w.r.t x</p> <p>$2x + 2y{{dy} \over {dx}} + \lambda = 0$ ....... (2)</p> <p>Using (1) and (2), eliminate $\lambda$</p> <p>${x^2} + {y^2} - \left( {2x + 2y{{dy} \over {dx}}} \right)x - 4 = 0$</p> <p>$2xy{{dy} \over {dx}} + {x^2} - {y^2} + 4 = 0$</p>

About this question

Subject: Mathematics · Chapter: Differential Equations · Topic: Order and Degree

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