I posted a question earlier and got the answer for $f(x)=x-\sqrt{x^2+5}$ .
I would like to know the oblique asymptote for $f(x)=x-\sqrt{x^2+5x}$
The function has a horizontal asymptote $y=\dfrac{-5}{2}$ when $x\to+\infty$. How do I find the oblique asymptote of this function when $x\to-\infty$?