Answer:
When x <= 8000
The cost remains constant at 0.35 when x increases from 0 to 8000
The slope of cost function over this part is 0
When 8000 < x <= 20000
The cost remains constant at 0.75 when x increases from 8000 to 20000
The slope of cost function over this part is 0
When 20000 < x <= 42000
The cost decreases when x increases from 20000 to 42000
The slope of cost function
[tex]m = \frac{y2 - y1}{x2 - x1} \\ = \frac{(0.83 - \frac{40000}{200000}) - (0.83 - \frac{20000}{200000})}{40000 - 20000} [/tex]
m= -5 × 10^-6
