About 2,500,000 results
Open links in new tab
  1. linear algebra - Prove that $A+I$ is invertible if $A$ is nilpotent ...

    Prove that $A+I$ is invertible if $A$ is nilpotent [duplicate] Ask Question Asked 13 years, 6 months ago Modified 5 years, 10 months ago

  2. When does the inverse of a covariance matrix exist?

    Oct 14, 2015 · We also know that every symmetric positive definite matrix is invertible (see Positive definite). It seems that the inverse of a covariance matrix sometimes does not exist. …

  3. Determine whether A is invertible, and if so, find the inverse. (3x3)

    If so, then the matrix must be invertible. There are FAR easier ways to determine whether a matrix is invertible, however. If you have learned these methods, then here are two: Put the matrix …

  4. When is $A^TA$ invertible? - Mathematics Stack Exchange

    Feb 26, 2023 · You'll need to complete a few actions and gain 15 reputation points before being able to upvote. Upvoting indicates when questions and answers are useful. What's reputation …

  5. What is the most efficient way to determine if a matrix is invertible?

    17 Gauss-Jordan elimination can be used to determine when a matrix is invertible and can be done in polynomial (in fact, cubic) time. The same method (when you apply the opposite row …

  6. Is every injective function invertible? - Mathematics Stack Exchange

    Sep 25, 2015 · A function is invertible if and only if it is bijective (i.e. both injective and surjective). Injectivity is a necessary condition for invertibility but not sufficient.

  7. linear algebra - Proof that columns of an invertible matrix are ...

    1 we want to proove that A is invertible if the column vectors of A are linearly independent. we know that if A is invertible than rref of A is an identity matrix so the row vectors of A are linearly …

  8. Why is only a square matrix invertible? - Mathematics Stack …

    Mar 30, 2013 · That a matrix is invertible means the map it represents is invertible, which means it is an isomorphism between linear spaces, and we know this is possible iff the linear spaces' …

  9. How do we know that if $Ax = b$ has a unique solution, $A$ is …

    Hi, I'm currently also thinking this problem out. I have some concerns however, how do you draw the conclusion that if A is not invertible, then there would be a non zero vector in its null space. …

  10. Why does a determinant of $0$ mean the matrix isn't invertible?

    3 I always got taught that if the determinant of a matrix is $0$ then the matrix isn't invertible, but why is that? My flawed attempt at understanding things: This approaches the subject from a …