Integrate functions of the form (x2+a2)−12(x^2 + a^2)^{-\frac{1}{2}}(x2+a2)−21 and (x2−a2)−12(x^2 - a^2)^{-\frac{1}{2}}(x2−a2)−21 and be able to choose substitutions to integrate associated functions.