Limit of root of x squared plus 5x minus x

As $x\to\infty$, what does $\sqrt{x^2+5x}-x$ tend to?

$\tfrac52$. Rationalising, $\sqrt{x^2+5x}-x=\dfrac{5x}{\sqrt{x^2+5x}+x}=\dfrac{5}{\sqrt{1+5/x}+1}\to\tfrac52$.