Question

The integrating factor of the differential equation $(1 + x^2) \frac{dy}{dx} + 2xy = \cos x$ is:

• A. $e^{x^2}$
• B. $1 + x^2$
• C. $\ln(1 + x^2)$
• D. $\frac{1}{1 + x^2}$

Hint:

If the numerator is the exact derivative of the denominator, the integral is simply the natural log of the denominator, yielding a direct simplification with the base $e$.

Answer 1

The Correct Option is B