Math Problem Statement

Solve6

A new 2014 luxury sedan that sold for $38,180 has a book value of $23,719 after t = 2 years. Find a linear and exponential model for the value V of the sedan over time.

Solution

Let's solve each part of this problem step-by-step.

Problem Statement Summary:

The problem involves a 2014 luxury sedan originally sold for $38,180. After 2 years, its value depreciates to $23,719. You are required to:

  1. Find a linear model for the value V(t)V(t) of the sedan.
  2. Find an exponential model for V(t)V(t).
  3. Graph both models to compare them.

Step 1: Linear Model

In a linear model, the value V(t)V(t) can be represented as: V(t)=mt+bV(t) = mt + b where:

  • tt is the time in years,
  • mm is the slope (rate of change of value per year),
  • bb is the initial value (value when t=0t = 0).

Calculate the Slope mm

Given data points:

  • (0,38180)(0, 38180) (initial value at t=0t = 0)
  • (2,23719)(2, 23719) (value after 2 years)

The slope mm is calculated as: m=V(2)V(0)20=23719381802=144612=7230.5m = \frac{V(2) - V(0)}{2 - 0} = \frac{23719 - 38180}{2} = \frac{-14461}{2} = -7230.5

Determine the Linear Model Equation

Now, we can write the linear equation as: V(t)=7230.5t+38180V(t) = -7230.5t + 38180


Step 2: Exponential Model

In an exponential model, the value V(t)V(t) can be represented as: V(t)=V0ektV(t) = V_0 e^{kt} where:

  • V0V_0 is the initial value at t=0t = 0,
  • kk is the decay constant.

Using the data points, we can solve for kk.

Since V(0)=38180V(0) = 38180 and V(2)=23719V(2) = 23719, we can set up the equation: 23719=38180e2k23719 = 38180 \cdot e^{2k}

Solving for kk:

  1. Divide both sides by 38180: 2371938180=e2k\frac{23719}{38180} = e^{2k}

  2. Take the natural logarithm of both sides: ln(2371938180)=2k\ln\left(\frac{23719}{38180}\right) = 2k

  3. Calculate the left side: k=ln(23719/38180)20.2282k = \frac{\ln(23719 / 38180)}{2} \approx -0.2282

Determine the Exponential Model Equation

Now, we can write the exponential equation as: V(t)=38180e0.2282tV(t) = 38180 \cdot e^{-0.2282t}


Step 3: Graphing Both Models

For graphing both models, we would use the equations derived:

  1. Linear Model: V(t)=7230.5t+38180V(t) = -7230.5t + 38180
  2. Exponential Model: V(t)=38180e0.2282tV(t) = 38180 \cdot e^{-0.2282t}

These equations should be graphed over the same time range to visually compare the depreciation of the sedan's value according to both models.


Would you like a further breakdown on any specific part or a graph illustrating these models? Here are some questions that expand on this:

  1. How does depreciation differ between linear and exponential models over longer periods?
  2. What are typical real-world examples where linear vs. exponential models might apply better?
  3. How would a different depreciation rate (slope or decay constant) affect the model?
  4. How can you calculate the rate of depreciation as a percentage for each year?
  5. How would you modify the models if you had a third data point?

Tip: In exponential decay models, kk (the decay constant) helps determine how quickly the value approaches zero. Smaller values of kk mean slower decay.

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Math Problem Analysis

Mathematical Concepts

Linear depreciation
Exponential depreciation
Algebra
Functions

Formulas

Linear model: V(t) = mt + b
Exponential model: V(t) = V0 * e^(kt)

Theorems

Slope formula
Exponential decay formula

Suitable Grade Level

Grades 10-12