If A, B, and C are all square matrices of the same size, show that AB commutes with C if A and B both commute with C.

All I know is

AC = CA

BC = CB

But I don't know what to do with that information to prove this.

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- February 23rd 2009, 07:53 AMpaulrb[SOLVED] Linear algebra matrix problem
If A, B, and C are all square matrices of the same size, show that AB commutes with C if A and B both commute with C.

All I know is

AC = CA

BC = CB

But I don't know what to do with that information to prove this. - February 23rd 2009, 07:57 AMJester
- February 23rd 2009, 08:03 AMpaulrb
Thanks, that's a lot easier than I thought. I guess I was thinking too hard.