(915, #5) Determine whether or not F(x,y) = < 1 + 4x3 y3, 3 x4 y2> is a conservative vector field. If it is, find a potential.

Solution: Write F = < fx , fy> for some f. Then:

Therefore the vector field is conservative.

To find the potential, f, we procede as follows:

We integrate fx with respect to x.

We then differentiate f with respect to y.

We compare this to the given fy find that g'(y) = 0, so g(y) = k. That is

f(x,y) = x4 y3 + x + k

by C.A.H.