1. The problem statement, all variables and given/known data A potential energy function for a two-dimensional force is of the form U = 3x3 * y - 7x. Find the force that acts at the point (x, y). 2. Relevant equations In a 1-dimensional case: ΔU = -∫Fx dx dU = -Fx dx Fx = -dU/dx 3. The attempt at a solution I know how to find the force in a 1-dimensional case; it's the gradient at the given x. But I can't wrap my head around it when there are two variables. Could it perhaps be the sum of the derivatives; Fx = -(dU/dx + dU/dy)?