Hi, Im having a little problem doing a question in mastering physics, I was wondering if anyone can help. here is the problem: A finite rod of length L has total charge q, distributed uniformly along its length. The rod lies on the x -axis and is centered at the origin. Thus one endpoint is located at (-L/2,0), and the other is located at (L/2,0). Define the electric potential to be zero at an infinite distance away from the rod. Throughout this problem, you may use the constant k in place of the expression 1/4*pi*epsilon_0. What is Va, the electric potential at point A (see the figure), located a distance d above the midpoint of the rod on the y axis? Express your answer in terms of k, q, d, and L. Here is what I have so far: r =sqrt(d^2+x^2) dV= k*(q/(2*(L/2)))*(dx/(sqrt(d^2+x^2))) V=K*(q/2*(L/2)))*(ln*((sqrt(d^2+x^2)+a)/(sqrt(d^2+x^2)-a)) *I got this from book* my problem is putting it all together, using k,q , d and L. especially the (ln*((sqrt(d^2+x^2)+a)/(sqrt(d^2+x^2)-a)) part, which does not want x in the answer. Im really lost. Thanks.