I have an expression obtain from an integral, which is:
Integrate[ϵ^2/Sqrt[(ϵ - u)^2 + Δ^2], ϵ] // FullSimplify
The denominator and numerator of the result have an obvious common factor:
Sqrt[Δ^2 + (u - ϵ)^2]
How can I let mathematica to cancel this common factor? I have tried
the variables to be positive.