Inclined asymptote can be found by calculating the limit of x*sqrt(2) - x, divided by x at x->+oo and x ->-oo
$$\lim_{x \to -\infty}\left(\frac{- x + \sqrt{2} x}{x}\right) = -1 + \sqrt{2}$$
Let's take the limitso,
inclined asymptote equation on the left:
$$y = x \left(-1 + \sqrt{2}\right)$$
$$\lim_{x \to \infty}\left(\frac{- x + \sqrt{2} x}{x}\right) = -1 + \sqrt{2}$$
Let's take the limitso,
inclined asymptote equation on the right:
$$y = x \left(-1 + \sqrt{2}\right)$$