1. The problem statement, all variables and given/known data The electric potential along the x-axis is V = 50x - (100/x)V, where x is in meters. What is E_x at x = 1.0m 2. Relevant equations partial derivative of dV/dx, then plug in the value for x 3. The attempt at a solution I understand the concept of trying to solve the equation you have to take the partial derivative of the equation with respect to x, when I do that I get 1-100(x), which is were I think I am going wrong. Der 50x would just be 1 Der 100/x =100x^-1 = -100x so when I put x=1 in for the equation and solve I do not get the right answer.