Problem 3. Given is the linear function $y=k x+n$, where $k, n \in\{-1,1\}$. Graphically represent all linear functions $y=k x+n$ on the same coordinate system, and then calculate the area of the region of the plane bounded by them.
The functions to be represented are: $\quad y=-x-1, \quad y=-x+1$, $y=x-1, \quad y=x+1 \quad$ (see diagram). The bounded area is a square with diagonal $d=2$, so the required area is $P=\frac{d^{2}}{2}=2$ sq.units.

![](https://cdn.mathpix.com/cropped/2024_06_05_dc4d34c0a9dd2a3ba572g-11.jpg?height=640&width=738&top_left_y=646&top_left_x=727)