Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Indefinite Integration

Question:

Integrating factor $\frac{dy}{dx}+ycotx=2x+x^2cot x (x≠0)$ is :

Options:

cosx

-sinx

sinx

-cosx

Correct Answer:

sinx

Explanation:

Given differential equation:

$\frac{dy}{dx}+y\cot x=2x+x^{2}\cot x,\ (x\neq0)$

This is linear form: $\frac{dy}{dx}+P(x)y=Q(x)$ with $P(x)=\cot x$.

Integrating factor $=\exp\!\Big(\int P(x)\,dx\Big)=\exp\!\Big(\int \cot x\,dx\Big)$

$=\exp(\ln|\sin x|)=\sin x$

Integrating factor = $\sin x$