Question

An online retail company determined that their cost for each day, x, can be determined by the function C(x) = 2x^2 – 20x + 70 and their revenue by the function R(x) = –x^2 + 5x + 18. How many days will it take for the company to earn a profit?

4
5
20
22

Answer 1

4

Explanation:

revenue has to be greater than cost for a profit

revenue minus cost = profit

2x^2 – 20x + 70 - (–x^2 + 5x + 18) =

2x^2 – 20x + 70 + x^2 - 5x - 18 =

3x^2 – 25x + 52 ≤ 0

(x - 4) (3x - 13) ≤ 0

x ≤ 4

x ≤ 13/3

since its multiple choice you can enter one of the answers where the x is to get the answer

if you don't know what the question is and are short on time this may help

again:

revenue has to be greater than cost for a profit

revenue minus cost = profit

cost is 2x^2 – 20x + 70

revenue is –x^2 + 5x + 18

cost is

2(4)^2 – 20(4) + 70 =

32-80+70 =

102-80 =

22

revenue is

–x^2 + 5x + 18

–(4)^2 + 5(4) + 18

-16+20+18

-16+38

22

--------------------------------

cost is

2(5)^2 – 20(5) + 70 =

20

revenue is

–(5)^2 + 5(5) + 18

18

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cost is

2(20)^2 – 20(20) + 70 =

470

revenue is

–(20)^2 + 5(20) + 18

-282

------------------------------

cost is

2(22)^2 – 20(22) + 70 =

598

revenue is

–(22)^2 + 5(22) + 18

-356

-----------------------------------------

cost is

2(3)^2 – 20(3) + 70 =

28

revenue is

–(3)^2 + 5(3) + 18

24

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cost is

2(2)^2 – 20(2) + 70 =

38

revenue is

–(2)^2 + 5(2) + 18

24