Linear algebra: inverse of the sum of two matrices

Click For Summary
SUMMARY

The discussion centers on proving the formula for the inverse of the matrix expression (I-A)^{-1} = I + A + A^2 + A^3, under the condition that A^4 = 0. Participants referenced a formula found in a Google Books resource and emphasized the importance of multiplying (I-A) by the series I + A + A^2 + A^3 to verify the identity. The problem was successfully resolved through this multiplication approach.

PREREQUISITES
  • Understanding of matrix operations, specifically matrix addition and multiplication.
  • Familiarity with the concept of matrix inverses.
  • Knowledge of nilpotent matrices, particularly the property A^4 = 0.
  • Basic proficiency in linear algebra concepts and notation.
NEXT STEPS
  • Study the properties of nilpotent matrices and their implications in linear algebra.
  • Learn about matrix series and their convergence, particularly in the context of inverses.
  • Explore the derivation and applications of the Neumann series for matrix inverses.
  • Investigate advanced topics in linear algebra, such as Jordan forms and their relevance to matrix inverses.
USEFUL FOR

Students and educators in linear algebra, mathematicians focusing on matrix theory, and anyone looking to deepen their understanding of matrix inverses and nilpotent matrices.

degs2k4
Messages
72
Reaction score
0

Homework Statement



Show that [tex](I-A)^{-1} = I + A + A^2 + A^3[/tex] if [tex]A^4=0[/tex]

The Attempt at a Solution



I found at Google Books some kind of formula for it:
http://books.google.com/books?id=UQ...PA44#v=onepage&q=inverse sum matrices&f=false

However, I think I should develop some kind of series for it using I = A(A^-1), I tried but I haven't been successful...

Thanks in advance.
 
Physics news on Phys.org
Just multiply (I-A) by I+A+A^2+A^3 and see if you get I.
 
Dick said:
Just multiply (I-A) by I+A+A^2+A^3 and see if you get I.

Thanks for your reply, got it solved!
 

Similar threads

  • · Replies 25 ·
Replies
25
Views
4K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 7 ·
Replies
7
Views
3K
Replies
0
Views
637
  • · Replies 6 ·
Replies
6
Views
2K
Replies
5
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 1 ·
Replies
1
Views
830
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 9 ·
Replies
9
Views
2K