Differential Equations — Class 12 Maths Solution

exemplar objective MCQ NCERT EXEMP.Q.49,Page.197
Question

The differential equation $y\frac{{dy}}{{dx}} + x = C$ represents

  • (a) family of hyperbolas
  • (b) family of parabolas
  • (c) family of ellipses
  • (d) family of circles ✓ Correct
Step-by-step Solution
Correct answer: option (d)

Given that, $y\frac{{dy}}{{dx}} + x = C$

$\Rightarrow$ $y\frac{{dy}}{{dx}} = C - x$

$\Rightarrow$ $ydy = (C - x)dx$

On integrating both sides,

we get
$\frac{{{y^2}}}{2} = Cx - \frac{{{x^2}}}{2} + K$

$\Rightarrow$ $\frac{{{x^2}}}{2} + \frac{{{y^2}}}{2} = Cx + K$

$\Rightarrow$ $\frac{{{x^2}}}{2} + \frac{{{y^2}}}{2} - Cx = K$

which represent family of circles.

NCERT & Exemplar solution for CBSE Class 12 Mathematics, Differential Equations. Curated by Sachin Sharma. Free for all students.