We have indeterminateness of type
oo/oo,
i.e. limit for the numerator is
$$\lim_{x \to \infty} x = \infty$$
and limit for the denominator is
$$\lim_{x \to \infty} \sqrt{x \left(x + 2\right)} = \infty$$
Let's take derivatives of the numerator and denominator until we eliminate indeterninateness.
$$\lim_{x \to \infty}\left(\frac{x}{\sqrt{x^{2} + 2 x}}\right)$$
=
Let's transform the function under the limit a few
$$\lim_{x \to \infty}\left(\frac{x}{\sqrt{x \left(x + 2\right)}}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{\frac{d}{d x} x}{\frac{d}{d x} \sqrt{x \left(x + 2\right)}}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{x \left(x + 2\right)}{\sqrt{x \left(x + 2\right)} \left(x + 1\right)}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{\frac{d}{d x} \frac{x \left(x + 2\right)}{x + 1}}{\frac{d}{d x} \sqrt{x \left(x + 2\right)}}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{- \frac{x^{2}}{x^{2} + 2 x + 1} - \frac{2 x}{x^{2} + 2 x + 1} + \frac{2 x}{x + 1} + \frac{2}{x + 1}}{\frac{x}{\sqrt{x^{2} + 2 x}} + \frac{1}{\sqrt{x^{2} + 2 x}}}\right)$$
=
$$\lim_{x \to \infty}\left(\frac{- \frac{x^{2}}{x^{2} + 2 x + 1} - \frac{2 x}{x^{2} + 2 x + 1} + \frac{2 x}{x + 1} + \frac{2}{x + 1}}{\frac{x}{\sqrt{x^{2} + 2 x}} + \frac{1}{\sqrt{x^{2} + 2 x}}}\right)$$
=
$$1$$
It can be seen that we have applied Lopital's rule (we have taken derivatives with respect to the numerator and denominator) 2 time(s)