If x represents the width of the poster (including borders), the area of the finished poster can be written as
.. a = x*(390/(x -10) +8)
.. = 8x +390 +3900/(x -10)
Then the derivative with respect to x is
.. da/dx = 8 -3900/(x -10)^2
This is zero at the minimum area, where
.. x = √(3900/8) +10 ≈ 32.08 . . . . cm
The height is then
.. 390/(x -10) +8 = 8 +2√78 ≈ 25.66 . . . . cm
The poster with the smallest area is 32.08 cm wide by 25.66 cm tall.
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In these "border" problems, the smallest area will have the same overall dimension ratio that the borders have. Here, the poster is 10/8 = 1.25 times as wide as it is high.
Answer:
A. He will have to work 40 hours to buy the headphones
B. 1200 ≤ 10.25x ≤ 2000 where x is # of hrs worked
He can work anywhere between 118 and 196 hours.
Step-by-step explanation:
A. Divide 399.95 by 10.25 to get 39.01 hours. But since you cant work 0.01 of an hour, you have to round up to the next hour
B. You want to make more than or equal to 1200, so put that in the inequality. You want to make less or equal to 2000, so you put that in the inequality. In the middle, you put 10.25 an hour multiplied by the number of hours, which is a variable.
To solve, I made 10.25x = 1200, and x equaled 117.07, which rounds up to 118 hours because you cant work a 0.07 of an hour. 118 hours is the low number of the spectrum.
To solve for the highest number on the spectrum, you do 10.25x = 2000, and x equals 195.12, but since you cant work 0.12 of an hour, it rounds up to 196 hours.
Answer:
Assuming this is the full problem.
3x^2-8x+4
Step-by-step explanation:
Answer:
Step-by-step explanation:
Huhuj
