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  1. Matrices - Conditions for $AB+BA=0$ - Mathematics Stack Exchange

    The Problem Let A A be the matrix (a c b d) (a b c d), where no one of a,b,c,d a, b, c, d is 0 0. Let B B be a 2×2 2 × 2 matrix such that AB+ BA= (0 0 0 0) A B + B ...

  2. How many ways can we get 2 a's and 2 b's from aabb?

    If I do this manually, it's clear to me the answer is 6, aabb abab abba baba bbaa baab Which is the same as \mathchoice((((4 2\mathchoice)))) \mathchoice ((((4 2 \mathchoice)))) But I don't really …

  3. 11 | abba, where a and b are the digits in a 4 digit number.

    Nov 21, 2013 · Truly lost here, I know abba could look anything like 1221 or even 9999. However how do I prove 11 divides all of the possiblities?

  4. sequences and series - The Perfect Sharing Algorithm (ABBABAAB ...

    Oct 4, 2016 · The algorithm is normally created by taking AB, then inverting each 2-state 'digit' and sticking it on the end (ABBA). You then take this entire sequence and repeat the process (ABBABAAB).

  5. How to calculate total combinations for AABB and ABBB sets?

    Apr 19, 2022 · Although both belong to a much broad combination of N=2 and n=4 (AAAA, ABBA, BBBB...), where order matters and repetition is allowed, both can be rearranged in different ways: …

  6. How many $4$-digit palindromes are divisible by $3$?

    Feb 28, 2018 · How many 4 4 -digit palindromes are divisible by 3 3? I'm trying to figure this one out. I know that if a number is divisible by 3 3, then the sum of its digits is divisible by 3 3. All I have done …

  7. elementary number theory - Common factors for all palindromes ...

    For example a palindrome of length $4$ is always divisible by $11$ because palindromes of length $4$ are in the form of: $$\\overline{abba}$$ so it is equal to $$1001a+110b$$ and $1001$ and $110$ are

  8. prove $\\Gamma(a)\\Gamma(b) = \\Gamma(a+b)B(a,b)$ using polar ...

    Jun 23, 2022 · Question: prove Γ(a)Γ(b) = Γ(a + b)B(a, b) Γ (a) Γ (b) = Γ (a + b) B (a, b) using polar transformation: my attempt: L.H.S =

  9. elementary number theory - Divisibility Tests for Palindromes ...

    The 4 4 -digit palindrome abba a b b a is divisible by 101 iff a = b a = b. The 5 5 -digit palindrome abcba a b c b a is divisible by 101 iff c = 2a c = 2 a. The 6 6 -digit palindrome abccba a b c c b a is divisible …

  10. Newest 'matrices' Questions - Mathematics Stack Exchange

    Jan 29, 2026 · For any topic related to matrices. This includes: systems of linear equations, eigenvalues and eigenvectors (diagonalization, triangularization), determinant, trace ...