How to show the direct sum of two matrices?

Click For Summary
SUMMARY

The discussion focuses on proving that the vector space V = Mat2x2(k) is the direct sum of the subspaces U and W, where U consists of matrices of the form {[a, b], [-b, a]} and W consists of matrices of the form {[c, d], [d, -c]}. The key steps involve demonstrating that the intersection of U and W is trivial (i.e., contains only the zero matrix) and that any matrix in V can be expressed as a sum of matrices from U and W. The approach includes equating elements from U and W to show that the only solution is the zero vector, confirming the direct sum property.

PREREQUISITES
  • Understanding of vector spaces and subspaces
  • Familiarity with matrix representation and operations
  • Knowledge of linear independence and basis concepts
  • Basic proficiency in field theory, specifically with fields denoted as k
NEXT STEPS
  • Study the properties of direct sums in vector spaces
  • Learn about linear independence and how to prove it in matrix forms
  • Explore the concept of basis and dimension in vector spaces
  • Review examples of direct sums in different fields, particularly in linear algebra
USEFUL FOR

Students studying linear algebra, mathematicians interested in vector space theory, and educators teaching concepts related to matrix operations and direct sums.

looper
Messages
2
Reaction score
0

Homework Statement


Let k be a field, V = Mat2x2(k), U:={[a, b], [-b, a] a, b E k} and W:={[a, b], [b, -a] a, b E k}. Show that V is the direct sum of U and W.


Homework Equations





The Attempt at a Solution



Add the matrix for U to the matrix of W. Values in that matrix still exist in k, so V = U + W. Is that the right reasoning? How do you show the intersection of two matrices is 0? Very confused.
 
Physics news on Phys.org
Write W={[c, d], [d, -c] c, d E k} to make it clear there are four independent parameters here. Equate an element of U with an element of W and show a=0, b=0, c=0 and d=0 from the equations you get. Then you have to show any element of V can be written as a sum of an element from U and an element from W.
 

Similar threads

Replies
15
Views
2K
Replies
5
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 6 ·
Replies
6
Views
4K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 13 ·
Replies
13
Views
11K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 5 ·
Replies
5
Views
13K