How would I prove that the product of a $n \times n$ matrix $A$ and its adjugate matrix $C^T$ (transpose of cofactor matrix $C$) $AC^T$ is diagonal ($AC^T$=$det(A)I$)? I've attempted to use cofactors and the fact that any non-diagonal element of $AC^T$ is the product of a cofactor and an element that shares a row with the elements of the cofactor, but I don't know where to go from there. Help is greatly appreciated!
2026-03-27 14:21:41.1774621301
Linear Algebra: How to prove that $AC^T$ is a diagonal matrix
105 Views Asked by Bumbble Comm https://math.techqa.club/user/bumbble-comm/detail At
1
There are 1 best solutions below
Related Questions in LINEAR-ALGEBRA
- An underdetermined system derived for rotated coordinate system
- How to prove the following equality with matrix norm?
- Alternate basis for a subspace of $\mathcal P_3(\mathbb R)$?
- Why the derivative of $T(\gamma(s))$ is $T$ if this composition is not a linear transformation?
- Why is necessary ask $F$ to be infinite in order to obtain: $ f(v)=0$ for all $ f\in V^* \implies v=0 $
- I don't understand this $\left(\left[T\right]^B_C\right)^{-1}=\left[T^{-1}\right]^C_B$
- Summation in subsets
- $C=AB-BA$. If $CA=AC$, then $C$ is not invertible.
- Basis of span in $R^4$
- Prove if A is regular skew symmetric, I+A is regular (with obstacles)
Related Questions in MATRICES
- How to prove the following equality with matrix norm?
- I don't understand this $\left(\left[T\right]^B_C\right)^{-1}=\left[T^{-1}\right]^C_B$
- Powers of a simple matrix and Catalan numbers
- Gradient of Cost Function To Find Matrix Factorization
- Particular commutator matrix is strictly lower triangular, or at least annihilates last base vector
- Inverse of a triangular-by-block $3 \times 3$ matrix
- Form square matrix out of a non square matrix to calculate determinant
- Extending a linear action to monomials of higher degree
- Eiegenspectrum on subtracting a diagonal matrix
- For a $G$ a finite subgroup of $\mathbb{GL}_2(\mathbb{R})$ of rank $3$, show that $f^2 = \textrm{Id}$ for all $f \in G$
Related Questions in DETERMINANT
- Form square matrix out of a non square matrix to calculate determinant
- Let $T:V\to W$ on finite dimensional vector spaces, is it possible to use the determinant to determine that $T$ is invertible.
- Optimization over images of column-orthogonal matrices through rotations and reflections
- Effect of adding a zero row and column on the eigenvalues of a matrix
- Geometric intuition behind determinant properties
- Help with proof or counterexample: $A^3=0 \implies I_n+A$ is invertible
- Prove that every matrix $\in\mathbb{R}^{3\times3}$ with determinant equal 6 can be written as $AB$, when $|B|=1$ and $A$ is the given matrix.
- Properties of determinant exponent
- How to determine the characteristic polynomial of the $4\times4$ real matrix of ones?
- The determinant of the sum of a positive definite matrix with a symmetric singular matrix
Related Questions in TRANSPOSE
- Vectorization and transpose: how are $\text{vec}(W^T)$ and $\text{vec}(W)$ related?
- What can we say about two bases A and B for which the conversion matrix to a third base C is the transpose of the other
- Decomposition of the product of matrices
- Interpretation of transpose of a linear application from a matricial product point of view
- Derivative involving trace and Kronecker product
- What does a matrix multiplied by its transpose tell me about the matrix's inverse?
- Proving similarity of $A$ and $A^T$
- What does it mean when you say a matrix of of a linear transformation is relative to a standard basis?
- Matrix equation $Z - {}^t Z =c A Z$
- Prove that the characteristic polynmial of a skew mapping satisfies $c(-\lambda) = (-1)^n c(\lambda)$
Trending Questions
- Induction on the number of equations
- How to convince a math teacher of this simple and obvious fact?
- Find $E[XY|Y+Z=1 ]$
- Refuting the Anti-Cantor Cranks
- What are imaginary numbers?
- Determine the adjoint of $\tilde Q(x)$ for $\tilde Q(x)u:=(Qu)(x)$ where $Q:U→L^2(Ω,ℝ^d$ is a Hilbert-Schmidt operator and $U$ is a Hilbert space
- Why does this innovative method of subtraction from a third grader always work?
- How do we know that the number $1$ is not equal to the number $-1$?
- What are the Implications of having VΩ as a model for a theory?
- Defining a Galois Field based on primitive element versus polynomial?
- Can't find the relationship between two columns of numbers. Please Help
- Is computer science a branch of mathematics?
- Is there a bijection of $\mathbb{R}^n$ with itself such that the forward map is connected but the inverse is not?
- Identification of a quadrilateral as a trapezoid, rectangle, or square
- Generator of inertia group in function field extension
Popular # Hahtags
second-order-logic
numerical-methods
puzzle
logic
probability
number-theory
winding-number
real-analysis
integration
calculus
complex-analysis
sequences-and-series
proof-writing
set-theory
functions
homotopy-theory
elementary-number-theory
ordinary-differential-equations
circles
derivatives
game-theory
definite-integrals
elementary-set-theory
limits
multivariable-calculus
geometry
algebraic-number-theory
proof-verification
partial-derivative
algebra-precalculus
Popular Questions
- What is the integral of 1/x?
- How many squares actually ARE in this picture? Is this a trick question with no right answer?
- Is a matrix multiplied with its transpose something special?
- What is the difference between independent and mutually exclusive events?
- Visually stunning math concepts which are easy to explain
- taylor series of $\ln(1+x)$?
- How to tell if a set of vectors spans a space?
- Calculus question taking derivative to find horizontal tangent line
- How to determine if a function is one-to-one?
- Determine if vectors are linearly independent
- What does it mean to have a determinant equal to zero?
- Is this Batman equation for real?
- How to find perpendicular vector to another vector?
- How to find mean and median from histogram
- How many sides does a circle have?
Hint: Each entry of $AC^T$ is the Laplace expansion of the determinant of some matrix. For the off-diagonal entries, this matrix has a repeated row.