Разложение в ряд:
$$\sqrt{2} - 1 + \frac{\sqrt{2} x}{4} - \frac{\sqrt{2} x^{2}}{32} + \frac{\sqrt{2} x^{3}}{128} - \frac{5 \sqrt{2} x^{4}}{2048} + \frac{7 \sqrt{2} x^{5}}{8192} - \frac{21 \sqrt{2} x^{6}}{65536} + \frac{33 \sqrt{2} x^{7}}{262144} - \frac{429 \sqrt{2} x^{8}}{8388608} + \frac{715 \sqrt{2} x^{9}}{33554432} - \sqrt{x} + O\left(x^{10}\right)$$