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3. A new television depreciates $120 per year, and it is worth $515 after seven years. Find a

function that describes the value of this television, if x is the age of the television in years. What

will the cost of the television be in thirteen years? If you had bought the television four years

ago, what was its selling price?

I do not see how this question is about quadratic functions.

"A new television depreciates $120 per year, and it is worth $515 after seven years."

total depreciation after 7 years: 7×$120 = $840

Purchase price = current value + total depreciation = $515 + $840 = $1,355

"Find a function that describes the value of this television, if x is the age of the television in years."

f(x) = 1,355 - 120x

"What will the cost of the television be in thirteen years?"

13·$120 > $1,355

After thirteen years, the television has no residual value.

"If you had bought the television four years ago, what was its selling price?"

I'm not sure what they mean by selling price, as the price of a new television was already found to be $1,355.

If they mean "how much could you sell it for today," its residual value is

f(4) = 1,355 - 120·4 = $875

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