Straight-Line Depreciation
Exponential Decay
Monthly Payment Formula
100

True/False: The equation for straight-line depreciation is given by the equation 

y = A(1-r)^x

False, this is the equation for exponential decay.

100

What does the A and r stand for in the equation 

y = A(1-r)^x?

A - initial amount.

r - interest (as a decimal).

100

What do P, r, t mean in the monthly payment formula?

P - principal amount

r - interest rate (as a decimal)

t - time in years.

200

True/False: The slope for the straight-line depreciation can be found by 

y = (x_2 -x_1)/(y_2 - y_1

False, the numerator and denominator need to be switched.

200

True/False: The exponential decay equation can also be thought of as y = (initial amount)(percent retained)x

True. If r is the percent lost, then (1-r) is the percent retained for the vehicle. 

200
True/False: To determine how much a vehicle costs long-term, we can multiply the monthly payment by the number of years. 

False, you must multiply by the number of months you make the payment for. 

300

The straight-line depreciation equation for a car is given by the equation 

y = -2150x +32000

What is the original price of the car and how much value does it lose each year?

It loses $2150 each year and its original price is $32,000.

300

The 24 Toyota Tacoma loses value very slowly. It loses value at only 1.5% each year. What is the exponential decay equation if the starting value of a 24 Toyota Tacoma is $31,590?

The exponential decay equation is 

y = 31590(0.985)^x

300

Baeza is considering getting a new truck. The trucks price is $32,000 and he was approved for a 4-year loan at 5.5%. What is the monthly payment?

The monthly payment is $744.21

400

Baeza's truck was $21,000 when he first purchased it. 5 years later, it has a value of $17,000. What is the slope for the straight-line depreciation equation?

Hint: This is how much value it loses each year. 

The slope for the straight-line depreciation equation would be 

m=-800

400

The exponential decay is equation for a vehicle is given by the equation 

y = 21000(0.97)^x

What is the value of the vehicle after 5 years?

The value of the vehicle is $18,033.41

400

Mrs. Baeza is considering getting a new Jetta. The trucks price is $27,000 and she was approved for a 4-year loan at 4.5%.What is the total amount of interest she would pay for this vehicle?

Mrs. Baeza will pay a total amount of $2,553.12 in interest. 

500

Mrs. Baeza's Jetta was worth $19,000 when it was first purchased. 8 years later, it has a value of $11,000. What is the straight-line depreciation equation for Mrs. Baeza Jetta? 

The straight-line depreciation equation is 

y = -1000x+19000

500
John bought a vehicle worth $33,333. It loses 3% of its value each year. 

1. Find the exponential decay equation.

2. How much is the vehicle worth after 3 years?

The vehicle is worth $30,422.13

500

Jake was approved for two loans for the same vehicle starting at $32,000.

The first loan is for 6 years with an interest rate of 3.9%.

The second loan is for 4 years with an interest rate of 5.1%.

Which loan will Jake pay the most interest on?

Jake will pay $3,941.68 in interest for the first loan, but he pays $3,442.72 for the second loan.

Therefore he pays the most amount of interest for the first loan. 

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