(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

show the set of nxn diagonal matrices is a group under matrix addition

2. Relevant equations

3. The attempt at a solution

it doesn't say what set the entries are from, so i'm assuming it's reals.

so i need to show that there is closure, it's associative, there's an identity element, and there's an inverse. i know that there's an identity element, the matrix with just zeroes, and i know the inverse is just -A for matrix A. it's addition, so i know that it's associative, and in my head i can tell that there is closure.

my main problem is notation. how to do i actually express this? i.e., what's the general notation for a nxn matrix?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Showing a set of matrices is a group

**Physics Forums | Science Articles, Homework Help, Discussion**