Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Differential Equations

Question:

The solution of the differential equation dy/dx + (y/x) = ex is-

Options:

xy = ex(x+1) +C

xy = ex(x-1) +C

xy = 2ex(x-1) +C

None of these

Correct Answer:

xy = ex(x-1) +C

Explanation:

The given differential equation is dy/dx + (y/x) = ex

which is of the form dy/dx + py =Q (Where p= 1/x and Q=ex )

Now, I.F. = e∫pdx

I.F. = e∫(dx/x)

So. I.F. = elogx = x.

The solution is given by: y.(I.F.) = ∫Q x(I.F.)dx +C

⇒ y.x = ∫(ex x x) dx +C

so. xy = ex(x-1) +C