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An electronics store is having a going-out-of-business sale. They have 220 computers in their inventory, and they believe they can sell 3 computers every day. If y represents the total number of computers in their inventory and x represents the number of days, which function rule describes this situation?
A. y=3x-220
B. y=220-3x
C. y=3(x-l)-220
D. y=220-3(x-1)

Respuesta :

twvogels
We know:
-->y(0)=220
-->dy/dx = -3
So int(dy=-3dx)=y=-3x+C
at y(0) --> 220=-3(0)+C
Therefore C= 220
Thus y=220-3x [] 

Answer:

B. y=220-3x

Step-by-step explanation:

Givens:

  • 220 computers are in the inventory.
  • They sell 3 computers per day.
  • x refers to days.
  • y refers to the total number of computers in the inventory.

Basically, the number of computer sold has to subtracted from the inventory, because those are articles that are going out, after being sold, they won't exist in the inventory anymore.

So, this difference between the existence in the inventory and the number of computer sold is best modelled by the second option, because the number of article sold has to subtracted from the inventory, not in the opposite way as the option A states.

If 220 computers is the existence in the inventory, that's the initial condition, which won't variate, because the number of articles in the inventory is represented by y. Also, if they sell 3 computers per day, the expression would be 3x.

Now, after we sell we take out the articles sold from the inventory, then, the function would be:

y = 220 - 3x

Therefore, option B is the answer.

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