Question

The integrating factor of the differential equation \[ (x + 2y^2) \frac{dy}{dx} = y, \quad (y > 0) \] is:

• A. \( \frac1x \)
• B. \( x \)
• C. \( y \)
• D. \( \frac1y \)

Hint:

Integrating factors simplify differential equations by making them exact.

Answer 1

The Correct Option is D

Step 1: Rewriting the equation
Divide through by \( y \): \[ \frac{1}{y} (x + 2y^2) \frac{dy}{dx} = 1. \]
Step 2: Find the integrating factor
The integrating factor \( \mu(y) \) is determined by identifying the dependency on \( y \) and multiplying the equation by \( \frac{1}{y} \).
Step 3: Verify integrating factor
After multiplying, the left-hand side becomes exact. The integrating factor is \( \frac{1}{y} \), which matches option (D).