Math Problem Statement

solve the set of recursion equations a_n = b_{n-1} + c_{n-1}, b_n = a_{n-1}+c_{n-1}, c_n=b_{n-1}+a_{n-1}

Solution

We are given a set of recurrence relations:

an=bn1+cn1a_n = b_{n-1} + c_{n-1} bn=an1+cn1b_n = a_{n-1} + c_{n-1} cn=an1+bn1c_n = a_{n-1} + b_{n-1}

Step 1: Analyze Symmetry

All three equations have similar structures. This suggests that the values of ana_n, bnb_n, and cnc_n might exhibit a symmetry, so solving one could give insight into the others.

Step 2: Combine the Equations

Add all three recurrence relations:

an+bn+cn=(bn1+cn1)+(an1+cn1)+(an1+bn1)a_n + b_n + c_n = (b_{n-1} + c_{n-1}) + (a_{n-1} + c_{n-1}) + (a_{n-1} + b_{n-1}) an+bn+cn=2(an1+bn1+cn1)a_n + b_n + c_n = 2(a_{n-1} + b_{n-1} + c_{n-1})

This simplifies to: Sn=2Sn1S_n = 2S_{n-1} where Sn=an+bn+cnS_n = a_n + b_n + c_n.

Step 3: Solve the Equation for SnS_n

The recurrence relation for SnS_n is: Sn=2Sn1S_n = 2S_{n-1} This is a geometric progression with the solution: Sn=S02nS_n = S_0 \cdot 2^n where S0=a0+b0+c0S_0 = a_0 + b_0 + c_0 is the initial sum of a0a_0, b0b_0, and c0c_0.

Step 4: Express ana_n, bnb_n, and cnc_n

Since the equations are symmetric, we can assume that ana_n, bnb_n, and cnc_n grow in a similar manner, and their individual forms can be derived from initial conditions.

For example, if we know initial conditions like a0a_0, b0b_0, and c0c_0, we can calculate subsequent values using the recurrence relations.

Do you have specific initial values for a0a_0, b0b_0, and c0c_0? This would help in fully determining the individual sequences.


Do you want more details or have any other questions?

Here are five questions to expand this:

  1. How does the solution change if a0=b0=c0=1a_0 = b_0 = c_0 = 1?
  2. Can we express each sequence individually if we modify one of the recurrence relations?
  3. What happens if one of the sequences is initialized to zero?
  4. How does this system behave asymptotically for large nn?
  5. What are the consequences of having non-equal initial conditions?

Tip: When working with recursive sequences, solving for the sum often simplifies the individual sequence relationships.

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Math Problem Analysis

Mathematical Concepts

Recursion
Sequences
Symmetry in Equations

Formulas

a_n = b_{n-1} + c_{n-1}
b_n = a_{n-1} + c_{n-1}
c_n = a_{n-1} + b_{n-1}
S_n = 2S_{n-1}
S_n = S_0 * 2^n

Theorems

Geometric Progression
Symmetry in Recursive Equations

Suitable Grade Level

Grades 10-12