$\underset{x\to -\infty }{\mathop{\lim }}\,\frac{\sqrt{-2x}+3}{1-\sqrt{-x}}=\underset{x\to -\infty }{\mathop{\lim }}\,\frac{\sqrt{-2x}}{-\sqrt{-x}}=\underset{x\to -\infty }{\mathop{\lim }}\,-\sqrt{\frac{-2x}{-x}}=\underset{x\to -\infty }{\mathop{\lim }}\,(-\sqrt{2})=-\sqrt{2}$