Answer:
[tex]C(x) = \$8 + \$0.05*x[/tex]
Step-by-step explanation:
Let 'x' be the usage in kWh. When usage is at or under 800 kWh, the cost function C(x) is given by the base charge of $8 added to the rate of $0.05/kWh multiplied by the consumption 'x', in kWh.
Therefore, for 0 ≤ x ≤ 800, the cost function is:
[tex]C(x) = \$8 + \$0.05*x[/tex]