The force exerted by an electric charge at the origin on a charged particle at point (x,y,z) is F(r) = kr/||r||^3, where k is a constant. Find the work done as the particle moves along a straight line from (3,0,0) to (3,4,5).
My answer is (1/3 - 1/square root of 50)*k, but it said it is wrong. I don't know why?