Question

The fee for charging an electric car at station A is $2 to start and $4 for each hour or fraction of an hour. Which point is NOT included in the graph of this step function?

A. (2.5, 14)
B. (2, 10)
C. (0,0)
D. (1,6)

Answer 1

Point A (2.5, 14)

Explanation:

The function for the charging fee, y, would be the initial $2 plus $4/hour for the charging time, x. This can be written as:

y = 4x + 2

Technically, both points A and C would not fall on theis line.

A: 2.5*4 + 2 = 12, not 12

C: at x = 0, there the equation still returns a $2 initial fee. So this should be (0,2) according to the equation. But it also makes sense to state that if the charging station is not used, there would be no charge. So a better way of expressing the equation would be to state that:

y = 4x + 2 for x > 0

Conclusion: Point A (2.5, 14) would not fall on this line.