Math Problem Statement

Let A 𝐴 be a 3 Γ— 3 3 Γ— 3 matrix and det ( A ) = 2 det ⁑ ( 𝐴 ) = 2 . If n = det ( adj ( adj ( … … . ( adj A )  2024 -times ) ) ) n = det ⁑ ( adj ⁑ ( adj ⁑ ( … … . ( adj ⁑ 𝐴 ) ⏟ 2024 -times ) ) ) Then the remainder when n n is divided by 9 is equal to ______.Read more on Sarthaks.com - https://www.sarthaks.com/3597222/let-abe-a-3-x-3-matrix-and-det-a-2-if

Solution

To solve the problem, we need to analyze the determinant properties of the adjugate matrix when it is repeatedly applied to a 3Γ—33 \times 3 matrix.

Key Observations:

  1. Adjugate and Determinants:

    • If AA is a 3Γ—33 \times 3 matrix, the determinant of the adjugate of AA is given by: det⁑(adj(A))=(det⁑(A))2.\det(\text{adj}(A)) = (\det(A))^{2}.
  2. Iterative Application:

    • Repeatedly taking the adjugate multiplies the determinant's power:
      • det⁑(adjk(A))=(det⁑(A))2k.\det(\text{adj}^k(A)) = (\det(A))^{2^k}.
  3. Given:

    • det⁑(A)=2\det(A) = 2.
    • We need to find: n=det⁑(adj2024(A)),n = \det(\text{adj}^{2024}(A)), which will be: n=(det⁑(A))22024=222024.n = (\det(A))^{2^{2024}} = 2^{2^{2024}}.
  4. Remainder modulo 9:

    • To simplify 222024mod  92^{2^{2024}} \mod 9, note that powers of 2 repeat in cycles modulo 9: 21≑2mod  9,β€…β€Š22≑4mod  9,β€…β€Š23≑8β‰‘βˆ’1mod  9,β€…β€Š24≑7β‰‘βˆ’2mod  9,β€…β€Š25≑5mod  9,β€…β€Š26≑1mod  9.2^1 \equiv 2 \mod 9,\; 2^2 \equiv 4 \mod 9,\; 2^3 \equiv 8 \equiv -1 \mod 9,\; 2^4 \equiv 7 \equiv -2 \mod 9,\; 2^5 \equiv 5 \mod 9,\; 2^6 \equiv 1 \mod 9. The cycle repeats every 6 terms.
  5. Exponent Simplification:

    • 22024mod  62^{2024} \mod 6:
      • Since 220242^{2024} is a power of 2, it is divisible by 4, so 22024mod  6=42^{2024} \mod 6 = 4.
    • Thus: 222024≑24mod  9.2^{2^{2024}} \equiv 2^4 \mod 9.
  6. Final Calculation:

    • 24=16≑7mod  92^4 = 16 \equiv 7 \mod 9.

Answer:

The remainder when n=222024n = 2^{2^{2024}} is divided by 9 is: 7.\boxed{7}.

Let me know if you'd like a detailed breakdown of any step or further clarification! Here are some related questions:

  1. What is the general pattern of powers of 2 modulo nn for different values of nn?
  2. How does the adjugate of a matrix behave under different dimensions?
  3. Can we generalize this approach for mΓ—mm \times m matrices?
  4. What would change if det⁑(A)\det(A) were negative or not an integer?
  5. How can this method be applied in cryptography or computational problems?

Tip: Always look for cyclical patterns in modular arithmetic to simplify large exponents.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Determinants
Adjugate Matrix
Modular Arithmetic
Exponentiation

Formulas

det(adj(A)) = (det(A))^2
det(adj^k(A)) = (det(A))^(2^k)
2^n mod 9 (cyclic pattern of powers of 2 mod 9)

Theorems

Properties of Determinants
Cyclic Properties in Modular Arithmetic

Suitable Grade Level

Undergraduate Mathematics