Help me with #4 pleasedeeee

Answer:
[tex]\dfrac{dy}{dx}=-\dfrac{2x-y-1}{2y-x-1}[/tex]
Step-by-step explanation:
Differentiating, you get ...
... x·dy +y·dx +dx +dy = 2x·dx +2y·dy
Collecting terms gives ...
... dy(x +1 -2y) = dx(2x -y -1)
... dy/dx = -(2x -y -1)/(2y -x -1)