Chapter 3 - The Derivative - 3.4 Definition of the Derivative - 3.4 Exercises - Page 176: 6

$-1$

We need to find the slope of the tangent line at $(2,2)$. We can do this by taking two points - for example $(2,2)$ and $(0,4)$ -, through which the aforesaid line passes through. The slope of the tangent s: $m = \dfrac{y_2-y_1}{x_2-x_1} = \dfrac{4-2}{0-2}=-1$.