Find the Z transform of the following discrete-time signals, remembering to include the region of convergence for each one. Use the definition of the Z transform and its properties
a. x(n) = u(n - 2)
b. x(n) = n - u(n - 1)
c. x(n) = e⁻³ⁿu(n - 1)
d. x(n) = 3.2ⁿu(-n)