When a commodity is sold for x dollars per item, the number of items sold is f(x). The item costs 5 dollars to make. The item costs 3 dollars to make. Required:
a. Express the total profit P in terms of x (the answer has been partially filled in for you).
b. What is the rate of change of the total profit as x changes?
c. If 3000 items sell when the price is 45 dollars and if the number of items that are sold decreases by 600 for every 1 dollar increase in price, find the rate of change of the profit when the item price is 45 dollars.

In may you used 400 kilowatt-hours of energy for electricity. a. calculate the total electrical energy use in joules. b. calculate your average power use in watts. c. assume that your power supplier generates electricity by burning oil. note that 1 liter of oil releases 12 million joules of energy. how much oil is needed to generate the electricity you use? give your answer in both liters and gallons. a. the total electrical energy use was nothing _ joules. (type an integer or a decimal.) b. the average power use is nothing _ watts. (round to the nearest whole number as needed.) c. to generate the electricity you used, nothing _ l is needed. (round to the nearest whole number as needed.) to generate the electricity you used, nothing _ gal is needed. (round to two decimal places as needed.)