Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Differential Equations

Question:

The correct solution of the differential equation (dy/dx) + y =1 where y≠1 is-

Options:

y= 1 + (1/C) e-x

y= 1 -(1/C) e-x

y= -1 -(1/C) e-x

y= 1 -(1/C) ex

Correct Answer:

y= 1 -(1/C) e-x

Explanation:

Given that differential equation

(dy/dx) + y =1

⇒ dy = (1-y) dx

separating the variables, we get:

dy/(1-y) = dx

now, integrating both sides we get:

∫dy/(1-y) =∫ dx

⇒ log(1-y) = x + log C

⇒ -log C - log(1-y) = x

⇒ log C(1-y) = -x

⇒ C(1-y)= e-x

y= 1 -(1/C) e-x