Math Problem Statement

Suppose a^n = -4an^(n-1) + 5a^(n-2) - 4a(n-3) and a^4 = -98, a^5 = 452, and a^6 = -2314. Find a^1,a^2,a^3

Solution

We are given the recurrence relation for ana^n as follows:

an=4an1+5an24an3a^n = -4a^{n-1} + 5a^{n-2} - 4a^{n-3}

Also, we are provided with:

a4=98,a5=452,a6=2314a^4 = -98, \quad a^5 = 452, \quad a^6 = -2314

Our goal is to find a1a^1, a2a^2, and a3a^3.

Step 1: Express the recurrence relation for specific values of nn

We will use the recurrence relation for n=6n = 6, n=5n = 5, and n=4n = 4.

Case n=6n = 6:

a6=4a5+5a44a3a^6 = -4a^5 + 5a^4 - 4a^3

Substitute a6=2314a^6 = -2314, a5=452a^5 = 452, and a4=98a^4 = -98:

2314=4(452)+5(98)4a3-2314 = -4(452) + 5(-98) - 4a^3

Simplify the terms:

2314=18084904a3-2314 = -1808 - 490 - 4a^3

2314=22984a3-2314 = -2298 - 4a^3

2314+2298=4a3-2314 + 2298 = -4a^3

16=4a3-16 = -4a^3

a3=4a^3 = 4

Step 2: Use the recurrence relation for n=5n = 5

a5=4a4+5a34a2a^5 = -4a^4 + 5a^3 - 4a^2

Substitute a5=452a^5 = 452, a4=98a^4 = -98, and a3=4a^3 = 4:

452=4(98)+5(4)4a2452 = -4(-98) + 5(4) - 4a^2

Simplify the terms:

452=392+204a2452 = 392 + 20 - 4a^2

452=4124a2452 = 412 - 4a^2

452412=4a2452 - 412 = -4a^2

40=4a240 = -4a^2

a2=10a^2 = -10

Step 3: Use the recurrence relation for n=4n = 4

a4=4a3+5a24a1a^4 = -4a^3 + 5a^2 - 4a^1

Substitute a4=98a^4 = -98, a3=4a^3 = 4, and a2=10a^2 = -10:

98=4(4)+5(10)4a1-98 = -4(4) + 5(-10) - 4a^1

Simplify the terms:

98=16504a1-98 = -16 - 50 - 4a^1

98=664a1-98 = -66 - 4a^1

98+66=4a1-98 + 66 = -4a^1

32=4a1-32 = -4a^1

a1=8a^1 = 8

Final Answer

Thus, the values of a1a^1, a2a^2, and a3a^3 are:

a1=8,a2=10,a3=4a^1 = 8, \quad a^2 = -10, \quad a^3 = 4

Would you like a more detailed explanation or have any questions?


Here are 5 related questions:

  1. How can you generalize recurrence relations for higher-order terms?
  2. What are other methods to solve recurrence relations besides substitution?
  3. How would solving change if the relation included a constant term?
  4. How can recurrence relations model real-world problems like population growth?
  5. What role do initial conditions play in determining solutions to recurrence relations?

Tip: In recurrence relations, always pay attention to the order of terms—it directly impacts how the sequence evolves.

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Math Problem Analysis

Mathematical Concepts

Recurrence Relations
Algebra
Sequences

Formulas

a^n = -4a^{n-1} + 5a^{n-2} - 4a^{n-3}

Theorems

Recurrence Relation Theorem

Suitable Grade Level

Grades 10-12