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TS EAMCET · Maths · Differential Equations

The general solution of the differential equation \(x \cos \frac{y}{x}(y d x+x d y)=y \sin \frac{y}{x}(x d y-y d x)\) is

  1. A \(\log (x y)=\log \cos \frac{x}{y}+C\)
  2. B \(\cos \left(\frac{y}{x}\right)=\frac{C}{x y}\)
  3. C \(\log (x y)=\log \sec \frac{x}{y}+C\)
  4. D \(x+y+C=0\)
Verified Solution

Answer & Solution

Correct Answer

(B) \(\cos \left(\frac{y}{x}\right)=\frac{C}{x y}\)

Step-by-step Solution

Detailed explanation

We have, \(x \cos \left(\frac{y}{x}\right)(y d x+x d y)\) \(=y \sin \frac{y}{x}(x d y-y d x)\) \(\Rightarrow \quad x y \sin \left(\frac{y}{x}\right) d y-y^2 \sin \left(\frac{y}{x}\right) d x\) \(=x y \cos \left(\frac{y}{x}\right) d x+x^2 \cos \left(\frac{y}{x}\right) d y\)…