1. The problem statement, all variables and given/known data I have to demonstrate the Uncertainty Principle Starting from the expression of the following ket: |Ψa>=(ax^+ibp^)|Ψ> where a and b are complex numbers and the ^ denotes that x and p are unitary vectors. 2.Relevant equations I must use the bra-ket notation, but I don't really have guidelines about the procedure to follow or the equations to use. 3. The attempt at a solution I thought about solving it trying to demostrate that <Ψa|Ψa> must be equal or greater to zero, but this implies integrate a expresion in two dimenssions of the phase space that I don't know how to solve. I though about using a projection operator, but all my tries went wrong, so I don't know if this is the right procedure. Thank you for your help.