Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Differential Equations

Question:

The differential equation representing family of circles with centre at point (4, 0) is :

Options:

$\frac{dy}{dx}=\frac{4-x}{y}$

$\frac{dy}{dx}=\frac{y}{4-x}$

$\frac{dy}{dx}=\frac{4+x}{y}$

$\frac{dy}{dx}=\frac{y}{4+x}$

Correct Answer:

$\frac{dy}{dx}=\frac{4-x}{y}$

Explanation:

The correct answer is Option (1) → $\frac{dy}{dx}=\frac{4-x}{y}$

$(x-4)^2+(y-0)^2=R^2$ → radius (arbitrary constant)

Differentiate w.r.t. x

$2(x-4)+2y\frac{dy}{dx}=0⇒\frac{dy}{dx}=\frac{4-x}{y}$