- #1

- 7

- 0

i can't find about how id prove it

i know A^2=A and A^-1 exists

so too AB=BA

its obvious to say elements must be 1 or 0 but finding an overal rule isnt obvious to me

- Thread starter keelejody
- Start date

- #1

- 7

- 0

i can't find about how id prove it

i know A^2=A and A^-1 exists

so too AB=BA

its obvious to say elements must be 1 or 0 but finding an overal rule isnt obvious to me

- #2

HallsofIvy

Science Advisor

Homework Helper

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If A has an inverse, multiply both sides of A^{2}= A by A^{-1}!

- #3

- 525

- 16

The proof above (HallsofIvy) is much more elegant, and applicable for all nxn matrices, but setting up the arbitrary matrix would probably be a good way to practice your matrix math.

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