- #1

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Second, If A and B are simliar matrices, show that if A is idempotent then so is B.

- Thread starter heidle12
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- #1

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Second, If A and B are simliar matrices, show that if A is idempotent then so is B.

- #2

Landau

Science Advisor

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First, any definition can be found on the internet. An idempotent is an 'element' a such that a^2=a. So an idempotent matrix is a matrix A such that [itex]A^2=A[/itex].

Second, what have you tried?

- #3

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A= A^2 then B=B^2

A^2 = B^2 then (AB)^2 = AABB = A^2B^2 = A = b

REALLY NOT SURE - NOT CONFIDENT IN MY THOUGHTS

- #4

Landau

Science Advisor

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This is what you need to prove.A= A^2 then B=B^2

You can't assume that A^2=B^2. Moreover (AB)^2=ABAB, which is not the same as AABB.A^2 = B^2 then (AB)^2 = AABB = A^2B^2 = A = b

The assumption is that A and B are

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