For part (a), the adjoint operator is
Using the canonical commutation relation ,
Thus and are the annihilation and creation operators of the quantum harmonic oscillator.
For part (b), write
Since and , differentiation of the unitary conjugation gives
The initial conditions are and . Solving this pair of linear ordinary differential equations gives the Bogoliubov transformation
This is the transformation implemented by the single-mode squeeze operator.
For part (c), invert the definition of :
The transformation above implies
The ground state has zero position and momentum means and variances and . Hence the squeezed vacuum state has
The reciprocal squeezing factors cancel, so
The state therefore continues to saturate the Heisenberg uncertainty relation.