The question:

Show that ||UX|| = ||X||.

My attempt

Say X = [x1 x2 ... xn]

Now I know that ||X||2 = <X, X> = |x1|2 ... |xn|2

I'm not sure where to go from here. Can anyone help?

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- Mar 29th 2010, 03:20 PMapple123Unitary Matrices
__The question:__

Show that ||UX|| = ||X||.

__My attempt__

Say X = [x1 x2 ... xn]

Now I know that ||X||2 = <X, X> = |x1|2 ... |xn|2

I'm not sure where to go from here. Can anyone help? - Mar 29th 2010, 04:28 PMtonio