# Expectation value of an operator in matrix quantum mechanics

## Homework Statement

Hey everyone.
Imma type this up in Word as usual:

http://imageshack.com/a/img577/3654/q9ey.jpg [Broken]

## Homework Equations

http://imageshack.com/a/img22/3185/pfre.jpg [Broken]

## The Attempt at a Solution

http://imageshack.com/a/img703/8571/xogb.jpg [Broken]

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Ohhh yea it isnt $cosh$, it should be $cos$...but is the rest okay? I mean the matrix U and stuff?