Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Differential Equations

Question:

General solution of the differential equation $\frac{2y\, dx-3x\, dy}{y}=0$ is

(c is an arbitrary constant)

Options:

$y=cx$

$y^3=x^2$

$y^3=cx^2$

$y=cx^2$

Correct Answer:

$y^3=cx^2$

Explanation:

$\frac{2ydx}{y}-\frac{3xdy}{y}=0⇒\frac{2ydx}{y}=\frac{3xdy}{y}$

$⇒\int\frac{2}{x}dx=\int\frac{3}{y}dy$  (integrating both sides)

$⇒2\log x=3\log y+\log c$ 

$⇒\log x^2=\log y^3c$

so $y^3c=x^2$

so $y^3=cx^2$