I need help solving the integral of an equation I came up with to model certain data. In the equation below, "a" and "b" are constants. Mathematica has an online integral solver, which somehow gave me imaginary numbers which isn't right. This function is just as real as any other function and I have worked with it. I've attached the image of what they gave me, mainly so you can see my original equation. I don't know what those funny A's with the squiggly lines above them are and I didn't put them into the equation originally. Look at the image as a guide for my equation. By the way, I have successfully found its derivative without any imaginary numbers. Thanks in advance.
http://integrals.wolfram.com/index.jsp?expr=%28b%C3%82%C2%B7%281+-+b^2%2F%28b^2+%2B+a^2%C2%B7TAN%28x%29^2%29%29^%281 %2F2%29%29&random=false