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The value V (in dollars) of a milling machine depends on the number of hours x it is operated as
given by the formula V = 750,000 - 120x. After one year, the value of the milling machine is
between $450,000 and $480,000.
Which range for the hours the machine is operated does this correspond to?

Respuesta :

Basically, you have to understand the logic of a function.

V = 750,000 - 120x

If I plug in a value into V that represents the value of a milling machine, if I simplify the equation, I will be able to find x, the corresponding time to the value of the milling machine.

Knowing this logic, we can plug in $450,000 and $480,000, and then we will have two x-values. Then we can just find the range of the x-values to find our answer! :)

Let's go.

V = 750,000 - 120x

Plugged in 450,000 for V so now we can simplify the equation and find out what is the corresponding x-value for this value at this certain time.

450,000 = 750,000 - 120x

-450,000  -450,000

0 = 750,000 - 120x

+120x on both sides to isolate x

120x = 300,000

x = 2500

So, our first x-value in the range is 6250 hours. Now, let's plug in the larger value to find out the other x-value in the range.

V = 750,000 - 120x

480,000 = 750,000 - 120x

-480,000  -480,000

0 =  270,000 - 120x

Add 120x on both sides to isolate x

120x = 270,000

x = 2250

So, we found 2250 and 2500. So, the range of hours it corresponds to is 2250-2500.