The potential field of an electric field E→=(yi^+xj^) is
V = -xy + constant
V = -(x + y) + constant
V = -(x2 +/)+constant
V = constant
dV=-E→·dr→ =-(yi^+xj^)·(dxi^+dyj^) =-(y d x+x d y)=-d(x y)
Integrating, we get V = -.xy+constant