Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Differential Equations

Question:

The solution of the differential equation $\frac{dy}{dx}= (1 + x^2)(1 + y^2)$ is (Here C is an arbitrary constant)

Options:

$\tan^{-1}y+x+\frac{x^3}{3}+=C$

$\tan^{-1}y-x-\frac{x^3}{3}+=C$

$\tan^{-1}x-y-\frac{x^3}{3}+=C$

$\tan^{-1}x+y+\frac{x^3}{3}+=C$

Correct Answer:

$\tan^{-1}y-x-\frac{x^3}{3}+=C$

Explanation:

The correct answer is Option (2) → $\tan^{-1}y-x-\frac{x^3}{3}+=C$

$\frac{dy}{dx}=(1+x^{2})(1+y^{2})$

$\Rightarrow \frac{dy}{1+y^{2}}=(1+x^{2})\,dx$

$\Rightarrow \tan^{-1}y= x+\frac{x^{3}}{3}+C$

$\displaystyle y=\tan\!\left(x+\frac{x^{3}}{3}+C\right)$