Suppose that a phone card has 400 min. Write a relationship that represents the number of minutes remaining r(x) as a function of the number of minutes already used x.

3) The area of a sheet of paper is 93.5 square inches. a. Find the remaining, visible area of the sheet of paper after it is folded in half once, twice, and three times. b. Express the visible area a of the sheet of paper as a function of the number of times it has been folded n. c. Use graphing technology to graph the function a. d. In this context, can the domain of a include negative values? Explain your reasoning. e. Can the range include negative values? Explain your reasoning.

The equation  =y 70001.08x  describes the growth of an investment (in dollars) based on the number of years it's been allowed to grow.   Part: 0 / 2 0 of 2 Parts Complete   Part 1 of 2       (a) Complete the table of outputs for this function,  =y 70001.08x . Feel free to use a calculator or spreadsheet. Round the value to the nearest cent.   Year Value 0   5   10   15   20

Suppose that a cost–benefit function is given by f (x) = 50x105 - x, 0 … x … 100, where x is the percentage of some pollutant to be removed and f (x) is the associated cost (in millions of dollars). Find the cost to remove 70%, 95%, and 100% of the pollutant.