Question

Andrew has a cell phone plan that provides 300 free minutes each month for a flat rate of $19. For any minutes over 300, Andrew is charged $0.39 per minute. Which of the following piecewise functions represents charges based on Andrew's cell phone plan?

Answer 1

19, x≤ 300

19+.39(x-300), x>300

Explanation:

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Answer 2

`f(x)=\left\{\begin{array}{l}19,\ \ x\le 300\\ \\19+0.39(x-300),\ \ x>300\end{array}\right.`

Explanation:

Andrew has a cell phone plan that provides 300 free minutes each month for a flat rate of $19. For any minutes over 300, Andrew is charged $0.39 per minute.

Let x be the number of minutes Andrew uses per month and f(x) be the charges based on Andrew's cell phone plan.

If
`x\le 300,` then
`f(x)=19.`

If
`x>300,` then first 300 minutes are free and each minute of next (x-300) minutes costs $0.39, therefore

`f(x)=19+0.39(x-300).`

Hence,

`f(x)=\left\{\begin{array}{l}19,\ \ x\le 300\\ \\19+0.39(x-300),\ \ x>300\end{array}\right.`