Hi

Find the gradient of the tangent on the curve $\displaystyle \frac{x}{\sqrt{2x}}$ at the point (4, $\displaystyle \sqrt{2x}$). Express your answer as a rational number.

The textbook's answer is $\displaystyle \frac{\sqrt{2}-2}{2}$ whilst I keep getting $\displaystyle \frac{\sqrt{2}}{8}$. Is the textbook right?