# Thread: Solving dy/dx = cot(x+y)-1.

1. ## Solving dy/dx = cot(x+y)-1.

hello guys, have tried but to no avail on this problem:

dy/dx = cot(x+y)-1

pls help out! thanks.

2. ## Re: varible seperable differencial equation. pls help!

Try a substitution: u = y + x. I think your DE will simplify considerably.

3. ## detail on problem am having on variable saparable diff. equation!

let me make it clearer guys;

the equation is dy/dx = cot(y+x)-1

solution is Cos(y+x)=ce-x

my problem is the process leading to the solution and was solved using variable saperable differencial equation

thanks for ur assistance.

4. ## Re: detail on problem am having on variable saparable diff. equation!

Originally Posted by lawochekel
let me make it clearer guys;

the equation is dy/dx = cot(y+x)-1

solution is Cos(y+x)=ce-x

my problem is the process leading to the solution and was solved using variable saperable differencial equation

thanks for ur assistance.
Substitute $y+x=u$

$\frac{dy}{dx}+1=\frac{du}{dx}$

5. ## Re: detail on problem am having on variable saparable diff. equation!

Originally Posted by lawochekel
let me make it clearer guys;

the equation is dy/dx = cot(y+x)-1

solution is Cos(y+x)=ce-x

my problem is the process leading to the solution and was solved using variable saperable differencial equation

thanks for ur assistance.
You were told what to do in post #2. Did you try following that suggestion? What have you tried? Where are you still stuck?