- #1

annoymage

- 362

- 0

if AB=BA for all B(2x2),

show that A=àI for all à € real number

its really hard to send new post using phone..

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- Thread starter annoymage
- Start date

- #1

annoymage

- 362

- 0

if AB=BA for all B(2x2),

show that A=àI for all à € real number

its really hard to send new post using phone..

- #2

CompuChip

Science Advisor

Homework Helper

- 4,309

- 49

Well, if you don't see any clever way to solve it (like me at first reading), you could simply take two matrices,

[tex]A = \begin{pmatrix} a & b \\ c & d \end{pmatrix}, \qquad B = \begin{pmatrix} x & y \\ u & v \end{pmatrix}[/tex]

and see what equations you get when you multiply AB = BA. Then note that this equations should hold for any values of x, y, u and v - allowing you to solve for a, b, c and d.

- #3

annoymage

- 362

- 0

before that,its hard to give my answer, so please teach me how to make that latex matrix.

- #4

CompuChip

Science Advisor

Homework Helper

- 4,309

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(If you want to use pmatrix in your own LaTeX documents, you have to \usepackage{amsmath}).

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