Math Problem Statement

The number of cars sold weekly by a new automobile dealership grows according to a linear growth model. When the dealers began tracking sales, the dealership had sold six cars (P_0 = 6). The first week the dealership sold eight cars (P_1 = 8). Write the recursive formula for the number of cars sold, P_N, in a particular week. Write the explicit formula for the number of cars sold, P_N, in a particular week. If this trend continues, how many cars will be sold in the fourth week?

Solution

Let’s solve the problem step by step:

Recursive Formula

The problem states that the number of cars sold weekly grows linearly. Based on the information:

  • P0=6P_0 = 6 (Initial value, cars sold at the beginning)
  • P1=8P_1 = 8 (Cars sold in the first week)

From P0P_0 and P1P_1, the growth rate (difference) is: P1P0=86=2P_1 - P_0 = 8 - 6 = 2 This means the dealership sells 2 more cars each week than the previous week.

The recursive formula is: PN=PN1+2P_N = P_{N-1} + 2

Explicit Formula

The explicit formula uses the initial value and growth rate: PN=P0+N(growth rate)P_N = P_0 + N \cdot \text{(growth rate)} Substitute P0=6P_0 = 6 and growth rate 22: PN=6+2NP_N = 6 + 2N

Number of Cars in Fourth Week

Using the explicit formula PN=6+2NP_N = 6 + 2N, substitute N=4N = 4 (fourth week): P4=6+24=6+8=14P_4 = 6 + 2 \cdot 4 = 6 + 8 = 14 Thus, 14 cars will be sold in the fourth week.

Final Answers

  1. Recursive Formula: PN=PN1+2P_N = P_{N-1} + 2
  2. Explicit Formula: PN=6+2NP_N = 6 + 2N
  3. Cars in Fourth Week: 1414

Would you like additional details or explanations? Here are some related questions to expand your understanding:

  1. What is the difference between recursive and explicit formulas?
  2. How can you calculate the growth rate if only two weeks' data are given?
  3. How would the formula change if the growth rate were negative?
  4. Can you graph the linear growth model using these formulas?
  5. What would the total number of cars sold over four weeks be?

Tip: Always verify formulas by testing known values to ensure correctness!

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Math Problem Analysis

Mathematical Concepts

Linear Growth
Recursive Formulas
Explicit Formulas
Arithmetic Sequences

Formulas

Recursive formula: P_N = P_{N-1} + 2
Explicit formula: P_N = 6 + 2N

Theorems

Arithmetic Sequence Formula

Suitable Grade Level

Grades 7-9