Answer:
4.5
Step-by-step explanation:
4 + y = -3
subtract 4 from each side
y = -3-4
y = -7
The conditions are needed to be able to answer the question
For
to be conservative, we need to have



Integrate the first PDE with respect to
:

Differentiate with respect to
:

Now differentiate
with respect to
:

So we have

so
is indeed conservative.