Chapter 3 - Section 3.3 - Differentiation Rules - Exercises - Page 136: 23

$f' = \frac{1}{\sqrt s(\sqrt s + 1)^{2}}$

$f = \frac{\sqrt s - 1}{\sqrt s + 1}$ $f' = \frac{(\sqrt s + 1)(\frac{1}{2}s^{-\frac{1}{2}})-(\sqrt s - 1)(\frac{1}{2}s^{-\frac{1}{2}})}{(\sqrt s + 1)^{2}}$ $f' = \frac{(\frac{1}{2}s^{-\frac{1}{2}})(2)}{(\sqrt s + 1)^{2}}$ $f' = \frac{1}{\sqrt s(\sqrt s + 1)^{2}}$